Best Temperature for Proofing Sourdough: Full Guide & How To

When it comes to sourdough baking, understanding the ideal temperature to proof/ferment your dough can be a bit of a challenge. Especially when you are trying to use temperature to give you predictable, consistent results. I’ve had the opportunity to make sourdough bread in both hot and cold extremes, and everything in between! Hopefully this post will help you use temperature to your advantage, so you can get the results you’re looking for.

What is the ideal temperature to ferment sourdough? Here are some very general guidelines:

• Ideally, your dough should be proofed in a draft free and humid area that will have a consistent temperature.
• Humidity levels of 60 – 80% work best for dough proofing.
• Sourdough tends to ferment best within a temperature range of 75F – 82F (25C – 28C), as this is the temperature that yeasts work well at.
• For a more sour and developed flavor, temperature ranges that are either above 82F (28C) or below 50F (10C) are ideal, depending on which sour notes you prefer, and how long you want to ferment for.

Now, the real question is:

• How do you obtain optimal temperatures?
• What are the benefits of changing the temperature of your dough?
• How can you control results to give consistency and more control over the result of your bread (including flavor consistency)?

If you’re ready to take your baking to the next level and gain a good understanding of how to get more consistent results that are perfectly unique to you, read on…This is going to be a full guide into everything I know about proofing temperatures when it comes to sourdough baking, and how you can manipulate temperature to give you consistent results every time.

NOTE: Throughout this article, ‘proofing‘ refers to bulk fermentation (1st rise), AND the 2nd proof after the dough is shaped. These words are usually used interchageably, and are sometimes known as ‘proving‘, or ‘rising‘. Of course, you are welcome to call it your own thing too, but I just wanted to make that clear right from the offset 🙂

Why Does Temperature Matter When Proofing Sourdough?

The temperature in which you proof sourdough, not only affects how long you need to ferment it for, but it also affects how well the yeasts and bacteria consume the sugars and in which proportions. This also affects flavor. Being able to control temperature, and understand how it affects the dough, will ultimately give you more control over:

1. How long you ferment/proof the dough for; giving you more control over your sourdough schedule.
2. The flavor of the bread; giving you consistency and control over the outcome.
3. Making the learning curve less steep towards nailing that perfect sourdough loaf!

Let’s be honest here, sourdough tends to have a mind of its own. So the more variables you are able to control, the more predictable your results will be. Of course, temperature is one those variables, but having a better understanding over temperature, will allow you to fit sourdough baking around your schedule, and not the other way round!

Let’s take a look at what the ‘ideal’ temperature for proofing dough is, and why this can vary so much when it comes to sourdough bread…

The Affect of Temperature on Sourdough Fermentation

Sourdough starter is made up of a complicated ecosystem of various bacteria and yeasts. Different strains of yeasts and bacteria thrive at different temperatures. This can be used to the bakers advantage to produce preferable results. Let’s dive in to some more detail to help figure out what you want out of your sourdough bread.

Why Does Proofing Temperature Affect the Flavor of Sourdough?

As mentioned earlier, the different bacteria and yeast found in sourdough starter will have different ‘optimal’ temperatures in which they ferment best. When yeasts are fermenting efficiently, they produce very little byproduct. BUT, these byproducts are what give sourdough bread it’s wonderful sour flavor. With this knowledge we can learn to manipulate the flavor of our bread.

• Yeasts tend to ferment most efficiently at 80F – 90F (27C – 32C). At this temperature range, they consume sugars from the dough with the least amount of byproduct, and will give bread a milder flavor.
• Bacteria strains tend to ferment efficiently at temperatures outside of those ranges, and this produces byproduct which affect flavor.
  • At higher temperatures, they produce lactic acid, which give one type of ‘base sour’ flavor.
  • At lower temperatures, they produce acetic acid, which give a different type of sour note, that has more of a ‘tang‘.

FUN FACT: Bakers often place their dough in a warm environment during the bulk rise, and then in the refrigerator for the 2nd rise. This helps to develop BOTH types of sourness in the loaf, giving you very complex and wonderful flavors!

The further away the temperature is from the optimal yeast fermentation range, the more byproduct is produced in the dough. The more byproduct, the more sour the flavor. The type of sourness is determined by which temperature the dough was proofed i.e. warm, short proofing time, or cool, long proofing time.

This table shows the flavor outcome of proofing at different temperature ranges, and their estimated proofing times:

	Temperature Range	Fermentation Time	Flavor Outcome
Hot (e.g. Very Hot Sunny Day)	82F – 85F (28C – 29C)	Short (4 – 6 hours)	Base Sourness
Warm (e.g. Room Temperature)	70F – 75F (21C – 24C)	Medium (6 – 12 hours)	Mild
Cold (e.g. Fridge Temperature)	35F – 50F (2C – 10C)	Long (12 – 24+ hours)	Tangy Sourness

NOTE: Fermentation times are an estimate, as they are also affected by how much sourdough starter was used in the dough. (More on that later)

What is the Ideal Temperature for Proofing Sourdough?

Taking into consideration the balance that you are looking for between fermentation time, efficiency, and flavor preference, it really boils down to 2 questions:

1. How long do you want to ferment for? (or, what will your schedule allow?)
2. What kind of flavor would you like?

The answer to these questions will make your ideal temperature for proofing sourdough bread. But, here’s a little guidance if you are unsure…

For beginner sourdough bakers, who perhaps haven’t acquired a taste for ‘sour’ bread just yet, the ‘mild flavor temperature zone’ (21C – 24C) is a good temperature to opt for. However, the most popular temperature to keep your dough, is between 75F and 82F (25C – 28C). This temperature gives your bread a nice warm environment to ferment in and has a good balance of sour flavors that are not too strong.

If you are looking for a more sour flavor, you’ll want to proof your dough further away from the mild flavor temperature zone in either direction, depending on wether you want a quick or slow fermentation time.

There are many other ways to manipulate the sourness of your sourdough bread. If you are interested in some general tips, have a read of my article “18 ways to make sourdough bread more (or less) sour”.

What Temperatures are Too Hot/Cold for Sourdough Fermentation?

Sourdough ferments well between 70F – 85F (21C – 30C), but it also has a pretty wide range of temperatures it can ferment in. Many bakers ‘retard’ their dough, by placing it in the refrigerator to give a very slow, long ferment, in order to develop a good sour flavor. So, you can say the dough is pretty hardy and can take a wide range of temperatures.

In fact, anything above freezing temperatures, and sourdough can still ferment, albeit VERY slowly. At the hotter end of the spectrum, after about 110F (43C), it’s possibly getting too hot. And if you live in a really hot part of the world, take a look at the next section explaining what we can do to control temperatures.

NOTE: If your dough is going to be in an environment of more than 95F (35C) then you should use cooler water and ingredients to begin with in order to slow down the fermentation process a little. Yeast tends to become dormant at temperatures above 95F (35C). Your dough will still ferment using the bacteria found in the sourdough starter, but the yeast needs to be somewhat active at least to begin with.

Now that we have an idea about what sort of temperatures we are looking for in our dough, let’s discuss what we can do to control the temperature when proofing sourdough.

How to Achieve the Ideal Temperature for Sourdough Fermentation

There are 2 aspects that you can control when it comes to temperature of proofing soudough.

1. Dough Temperature
2. Proofing Environment

Controlling the dough temperature at the initial phase of making sourdough, when coupled with controlling the temperature of the environment it ferments in, will give you consistent flavors, fermentation times, and all round predictable results.

The ideal temperature you want your dough to be is called the ‘Desired Dough Temperature’ or ‘DDT‘. (And this is the temperature you also want to proof/ferment your dough in). Let’s take a look at how we can obtain our DDT by changing the temperature of your ingredients…

In my online course, I go through in detail how to use temperature to fit sourdough baking into your schedule, as well as working with different flours and hydration levels. Check it out here.

The Temperature of Ingredients

The ingredients you use can be used cold or warm depending on what you want your dough temperature to be. The main ingredients that contribute to the final temperature of your dough in traditional sourdough bread are:

• leaven/preferment
• flour
• water

The easiest ingredient to adjust is your water temperature. We’re going to dive deeper into how to calculate what temperature water to use, in order to get the desired dough temperature. But first we need to understand another factor that will affect dough temperature…

The Method Used to Make the Dough

The method you use to mix your dough will have an affect on dough temperature. If you hand mix your dough, then it will produce little to no heat. But if you use a mixer to make your dough, then the process of using the mixer will add extra heat, giving your dough a warmer temperature. This heat from mixing the dough is known as the ‘friction factor‘.

How to Measure Friction Factor

Friction factor can be estimated according to the method you use to make your sourdough. I only ever use stretch and folds for my sourdough, which produces minimal heat, making the friction zero.

But if you are using a mixer for around say 5 minutes, then you can estimate a friction factor of around 20. The longer you mix, the higher the friction factor. Kneading by hand for about 8 minutes (the standard time for many doughs) will give a friction factor of about 8. Here’s a quick table to help you estimate what your friction factor may be (and don’t worry, an estimate is just fine):

Sourdough Mixing Method	Friction Factor (estimation)
‘Stretch and Fold’ or ‘No knead’ method	0
Hand kneading for 8 – 10 minutes	8
Using a stand mixer for 5 – 6 minutes	20

How to Reach your Desired Dough Temperature (DDT)

First, use a good quality food thermometer like this one (Amazon link) to check the temperature of all of your ingredients, and then adjust your water temperature accordingly. Bear with me if it looks like it doesn’t make a lot of sense at first, we will be following it with a couple of examples to show that it’s not as complicated as it seems:

• Step 1 – Decide what you want your dough temperature to be
• Step 2 – Measure the temperature of your
  • flour
  • leaven (if you are using one)
  • room temperature
• and make a note of the temperature of each one.
• Step 4 – Consider what your Friction Factor will be (an estimate is fine).
• Step 3 – Use the following calculations to figure out what your water temperature should be:
  • If using a leaven:
    • DDT multiplied by 4 (because you are measuring 4 things)
  • If NOT using leaven:
    • DDT multiplied by 3 (because you are measuring 3 things)
• The answer will give you your Total Temperature Factor (TTP)
• Step 4 – Subtract all the following from the TTP:
  • room temperature
  • flour temperature
  • leaven/preferment
  • friction factor
• The number you are left with will be what you need your water temperature to be.

Let’s take a couple of different examples:

In the first example, I am going to be using a leaven, and hand mixing using stretch and folds only. Let’s go through the steps:

• Step 1 – I want my dough temperature to be 72F
• Step 2 – I make note of the following measurements using my thermometer:
  • room temperature = 70F
  • flour temperature = 65F
  • leaven = 70F
  • friction factor = 0 (this is because I using only stretch and folds which produce a negligible heat)
• Step 3 – As I am using a leaven, I will multiply my DDT by 4
  • 72 x 4 = 288 (this is my TTP)
• Step 4 – Subtract all the above numbers from the TTP
  • 228 – 70 – 65 – 70 – 0 = 83F
  • My water temperature needs to be 83F if I want my dough temperature to be 72F.

In the 2nd example, I am NOT using any leaven or preferment, and I will be mixing the dough in my Kitchen Aid for 5 minutes. Let’s go through the steps again:

• Step1 – I want my dough temperature to be 65F, as I want a colder, longer ferment with a more developed flavor.
• Step 2 – I make note of the following measurements using my thermometer:
  • room temperature = 50F (I will be refrigerating my dough)
    flour temperature = 70F
    friction factor = 20 (this is an estimation based on 5 minutes of mixing with a KithenAid)
• Step 3 – I’m NOT using a leaven, so I will multiply my DDT by 3
  • 65 x 3 = 195 (this is my TTP)
• Step 4 – Subtract all the above numbers from the TTP
  • 195 – 50 -70 – 20 = 55F
  • My water temperature needs to be 55F if I want my dough temperature to be 65F

QUICK TIP: If you want your dough to be even cooler, or if you are making your dough in a particularly hot environment, flour can be stored and used straight from the fridge or even the freezer. This can contribute towards getting a colder dough.

Best Way to Control your Water Temperature:

These 2 methods work equally well, although I prefer using the 2nd method, as I find it is quicker to get the water to the temperature you need.

• Method 1 – Put your water in the microwave for 30 seconds at a time, checking the temperature each time as you go, until you reach the desired temperature.
• Method 2 – Use a little ‘just boiled’ water, and then add cold water to it until you get the right temperature.

QUICK TIP: When preparing your water, always start off with more water than you’ll need. This will stop the scenario of having too little, and then your water cooling down before you get a chance to prepare more!

Hopefully these examples have shown you how to get precise temperatures in your dough. Now we can discuss how you can control proofing temperature to help give you further control over your sourdough consistency.

How to Control Proofing Temperature for Sourdough

The most consistent and convenient way by far that I have found is to use a dough proofer. This one (Amazon link) is my absolute favorite as it gives you the versatility to adjust the temperature to whatever you wish. And as a bonus, it also gives you the option of adding humidity to the environment (see section below) AND it folds away flat, which is perfect for me as I don’t have a lot of counter top space!

Here’s a link to the same dough proofer if you’d like to buy from a lovely family owned company that specialize in artisan bread baking equipment! They are extremely knowledgeable and are always willing to go that extra mile whenever I’ve reached out to them.

If you don’t want to invest in a dough proofer though, there are make shift ways for you to control the temperature of your dough’s proofing environment. The most important thing to bear in mind is to keep your dough away from drafts. An area where your dough is exposed to too many fluctuating temperatures (such as a drafty area) will not give your sourdough a chance to ferment consistently. Cover it well and place it somewhere in your home that is draft free. Some good make shift areas that may work for you are:

• On top of your refrigerator
• On your counter top away from windows (corner areas work well)
• In your microwave with the door closed
• In a kitchen cupboard (in a warm part of your kitchen)
• In the oven (switched off of course! Although having the light on is a way to have it warmer in there)

Keep a thermometer next to your dough to keep tabs on the temperature. If you want it to be warmer or cooler, it is better to keep the dough in a closed space like an oven or microwave, as you can always then add a hot water bottle or an ice pack in there to help with temperature regulation.

You may want to periodically check the temperature of your dough just to be sure. The same thermometer is also pretty handy for checking the internal temperature of your bread, to check if it is properly cooked.

My online course shows you how to use techniques like temperature regulation and more to help with your scheduling. Check it out here!

Is Humidity Important for Sourdough Fermentation?

Sourdough ferments better in a more humid environment than it does in a drier environment. Humidity helps fermentation to occur optimally, and stops the dough from producing a film on top. Ideally, you want humidity levels of 60-80%. Having a room thermometer with a humidity checker built in like this one is useful. You can then decide if you need to add moisture to the area or not. You can encourage humidity by:

• Covering your dough – the best way to encourage humidity is to put a bowl upside down over the dough container.
• Placing a cup of hot water next to the dough to produce some steam in the area – this works particularly well if you place your dough in an enclosed space.
• The dough proofer I mentioned earlier comes with a water tray underneath, giving you the optimal humidity levels for sourdough of 60-80%. (For more information about this dough proofer and other products I love, check out my Baking Tools section).

Estimating Fermentation Times

Once you have temperature controlled environments for your dough, it is very easy to predict how long your dough will take to fully ferment, but here are few useful things to bear in mind when adjusting your recipes:

For every 15F (8C) drop in temperature, sourdough fermentation time doubles.

The above fact is useful to refer back to when deciding how to use temperature to your advantage when making sourdough. It will help you to adjust your temperatures to fit in with your schedule.

Using Alternative Flours will Affect Fermentation Times

If you are going to be using flours other than strong white bread flour, you should bear in mind that they may naturally ferment at a different rate. Let’s go through the most common ones and how they will affect your proofing times:

• Rye Flour – Rye flour is well known in sourdough baking. It has an extremely high enzyme activity level, which means it ferments at a much faster rate. If you are going to be adding rye flour to your dough, be sure to expect it to ferment faster. You can either shorten your fermentation time, or place dough at a cooler temperature to fit in with your regular schedule. (Have a read of my article here if you’d like more information on using rye in sourdough).
• Whole grain flour – Because whole grains contain the fiber and bran, these act as ‘extra food’ for wild yeasts and bacteria to feed on, making the fermentation time quicker. Again, you can reduce your DDT and proofing temperature by a few degrees to off set any whole grain you have added to your dough.
• Freshly milled flour – this flour ferments very quickly, so it helps to have a much cooler temperature when working with freshly milled flour, particularly if you have kept all the bran in it too.

If you’d like more specific and detailed information about using different flours in your sourdough breads, check out my ‘Full Guide to Using Different Flours in Sourdough Bread’.

If you Don’t have a Dough Proofer…

Not having a dough proofer means you may be a bit more limited to how much you can control the temperature. But here are some other ways in which you can make it work for you:

Use a Different Amount of Sourdough Starter

A smaller amount of starter will increase the fermentation time, and a larger amount of starter will decrease the fermentation time. To give you an idea, if one third of your dough is made up of sourdough starter, then the fermentation time will be around 4 hours at a temperature of 72F (22C). Use less, and the fermentation time will increase in proportion to how little you use.

NOTE: One third sourdough starter, and 4 hours fermentation time should be the maximum amount of starter, and the minimum amount of fermentation, in order for the sourdough to maintain it’s structure and integrity.

Start off with a Cooler or Warmer Dough Tempearature

Using the calculation I mentioned above, control your dough temperature to help offset the lack of control you have over the proofing temperature. For example, in the summer you can make your dough cooler, and in the winter you can make it warmer. This will help give you a little more consistency.