How Temperature Affects Sourdough

Throughout my years of baking bread and working with dough, I haven’t always fully appreciated how significantly temperature affects the dough. I’ve always known my rises take longer in the winter and often go faster in the summer, but only when I started working with sourdough bread did I realize how much temperature affects sourdough, and how important it is in baking.

Why I Always Use a Baking Thermometer

I can’t tell you how many times I thought my dough was warm enough, only to check the temperature and realize it wasn’t even close. That’s why I’m such a big advocate for using a good baking thermometer.

Being able to check your dough’s temperature helps you:

• Predict when it’ll be ready to shape or bake
• Adjust proofing time based on actual dough temperature
• Avoid under- or over-proofing, especially in tricky seasons

It’s also super helpful when checking if your bread is fully baked. Most sourdough loaves are done when the internal temp hits 190–210ºF, depending on how enriched the dough is.

After years of trial and error (and way too many Amazon duds), Thermoworks is hands-down my favorite thermometer brand. They’re fast, accurate, and easy to use—and honestly, they’ve saved me from so many baking headaches. These are my favorites for bakers:

• ThermoPop 2: Great for a beginner, Affordable, 2-3 second readings, reliable.
• Thermapen One: My favorite! Fast – within 1 second of accurate temperature readings and reliable.

Thermoworks is an incredible company and my husband uses them for all his grilling/smoking needs, so definitely check them out if you need a good quality thermometer.

Manipulating Dough Temperature through water

The temperature of your ingredients matter when mixing sourdough bread – some more than others. Of all the ingredients added, water is a key ingredient that is really easy for us to control the temperature of. This means that we can be strategic when adding water and make it warmer or colder to compensate if the starter/levain/dough temperature is not what we want it to be.

• If you want your dough warmer – add warm water when mixing.
• If you want your dough cooler – add cool water when mixing.

Example: Using a thermometer, I quickly check the temperature of the flour, salt, and levain. They are all under 70ºF. It is winter, so I know the ambient temperature is in the 60s. I add hot (90-95ºF water) to my dough and mix it together. Then, I take the temperature of the dough after mixing it. It is 70ºF. I put my dough in a bread proofer set at 78ºF (or other warm place). I know that my dough may take a little longer to ferment because the dough temperature is cooler than it should be.

New to Sourdough? If you are new to sourdough, learn how to make a sourdough starter from scratch and check out my Free Sourdough Beginner Guide. Using naturally fermented sourdough will take much longer, but you will love the fermentation benefits and the flavor!

What happens when it’s too hot or too cold?

Sourdough thrives best between 74–86°F, with the sweet spot around 76–80°F. The more consistently you can keep your starter, levain, and dough in that range, the more predictable your results will be. Here’s what happens when your sourdough drifts too far in either direction:

• Too Cold (68ºF and below): At these cold temperatures, fermentation will slow way down, take much longer to rise (or not rise at all), have dense texture and can lead to underproved bread.

• Too Hot (90ºF or above): If the temperature is too hot, fermentation will speed up. This can lead to overly sour flavor and dough that breaks down fast. It can also lead to weak structure and gummy crumb and temperatures over 120ºF can kill your yeast completely. Personally, I avoid using water over 100ºF when mixing dough to protect my sourdough starter.

How to Keep Sourdough Warm

In the winter, my house is cold (in the 60ºFs) and that cold temperature slows my sourdough way down. While long, slow rises can be great for flavor, sometimes you need a little help to keep things moving. Here are a few easy ways I warm up my dough in cooler temps:

1. Sunny Window, Warm Room, warm appliance

• If the sun is shining, a warm windowsill, a cozy bathroom or a warm appliance (the top of my dishwasher or refrigerator often works) can be great places to keep rising dough or sourdough starter.

2. Oven with the Light On

• Pop the dough into your oven with just the light turned on.
• This creates a warm space, perfect for proofing. Every oven is a little bit different, though, and you may need to move the starter around so it’s not directly under the oven light. It can sometimes get too hot in the oven, so you may need to move the starter or dough back and forth out of the oven to adjust the temperature.
• Warning: Be careful not to preheat your oven while the dough or starter is in there! Stick a sign or sticky note on the oven reminding you the oven is occupied with your starter so you don’t accidentally bake it.

3. Microwave or Cooler Trick

• Place a mug of hot water in the microwave, then put your covered dough next to it and close the door.
• The warm, steamy environment helps boost the temperature and acts as a pseudo-proofing box.

4. Heating Pad or Dough Mat

• A seedling mat is an inexpensive and easy way to get warmth to a starter. These mats typically don’t have the temperature controls of a dough mat so be sure to use a towel as a buffer.
• Dough Mat: I like the large size from Bakehouse Essentials (code: AMYBAKESBREAD10 for 10% OFF, affiliate link). This can easily fit your starter and a pan of sourdough dinner rolls and keeps the temperature consistent. Stick a towel underneath the dough mat to help insulate the warm temperatures.

5. Bread Proofing Box

• Proofing Box: I recently purchased this Brod & Taylor proofing box. I absolutely love it. It folds up easily for storage and has made a huge difference in keeping my sourdough right in that 78ºF range.

How to Keep Sourdough Cool for Warm Climates

Warm temperatures and high humidity can speed up fermentation, leading to over-proofed dough or a sourdough starter that’s hard to manage. Here are a few easy ways to keep things cool.

1. In and Out of the Fridge

• Use your fridge to slow things down.
• Take the temperature of the dough. If it’s in the mid-80ºF or higher, put it in the fridge for the first 30 minutes. Then take the temperature again and bring it out of the fridge if it’s dropped into the desired 76-80ºF range. Continue this process in and out of the refrigerator throughout the bulk fermentation as needed.
• Proof the dough in the refrigerator overnight.

2. Cooler with Ice Packs

• A portable cooler with a couple of ice packs can act like a mini fridge.
• Use a thermometer to monitor the dough temperature, aiming for around 76-80°F.

3. Sourdough Home (Temperature-Controlled Box)

• Devices like the Brod & Taylor Sourdough Home give you control over the temperature of your sourdough starter. It’s not big enough for your dough, but can help you control the fermentation of your starter.
• This is a great investment if you’re baking often in a hot climate.

These two loaves of sourdough sandwich bread were proofed for the same amount of time but at different temperatures. Notice the difference! The loaf on the left proved at 78 degrees with the dough temperature being 78 degrees. The one on the right the dough temperature was 10 degrees cooler.

Frequently Asked Questions

Looking for in-depth Sourdough instruction?

You need my online sourdough course.

• Step by Step Instruction on Beginner and Advanced Recipes
• 2+ hours of pre-recorded video instructions
• Community forum to ask questions and help you troubleshoot
• 15+ PDF recipe downloads
• Make incredible sourdough bread today!