Why Temperature Matters for Sourdough

If you take away one thing from this article, let it be this: temperature is the single biggest factor controlling how your sourdough behaves, and once you understand it, everything else clicks into place

KITCHEN & HEARTH

8/27/20262 min read

If your sourdough results feel random, temperature is almost always the missing variable. Here is exactly why temperature matters, and how to use it to your advantage.

The Basic Rule

In a nutshell: cooler temperatures slow fermentation down. Warmer temperatures speed it up. That is genuinely most of it. Wild yeast, the kind that lives in your starter, thrives in warmth and becomes sluggish in the cold. This single relationship explains almost every “why did my dough do that” question you will ever have.

Why This Matters for Your Starter

A starter kept at room temperature will need feeding daily, sometimes twice daily in warm weather, because the yeast is working through its food supply quickly. A starter kept in the fridge slows right down, meaning you can get away with feeding just once a week if you use a high enough feed ratio. Neither approach is wrong, but they suit very different lifestyles. If you are not baking daily, a fridge-stored starter uses far less flour and creates far less discard.

Why This Matters for Your Levain

When you build a levain (the portion of starter you mix specifically to use in a dough, kept separate from your maintenance starter), temperature dictates how long it takes to reach peak. A levain kept at around 26 degrees Celsius might peak in 3 to 4 hours, while the same levain left at a cooler room temperature could take 8 hours or more. Once you know how your levain behaves at a given temperature, you can plan your entire baking day around it, rather than checking on it anxiously every hour.

Why This Matters During Bulk Fermentation

Bulk fermentation is the stage between mixing your dough and shaping it, and it is where temperature control genuinely makes or breaks a bake. A warm dough ferments quickly and can easily overproof if you are not paying attention. A cool dough ferments slowly and gives you more of a safety margin, but takes longer to be ready.

This is also why using warm water when mixing your dough is so useful. Rather than relying purely on an external heat source to slowly warm up a cold dough, starting with warm water gives your dough a head start on temperature, which then just needs maintaining rather than building from scratch.

Why This Matters During Cold Proofing

Once your dough is shaped, moving it to the fridge for a cold proof slows fermentation right down again, which is exactly the point. It gives you flexibility (you can bake the next morning, or leave it for up to 3 days), and it develops a deeper, more complex sour flavour the longer it sits. Your dough does still continue to rise slowly in the fridge, just at a much slower rate than at room temperature.

The Real Benefit of Controlling Temperature

The honest reason temperature control matters so much is consistency. If you use the same ingredients and the same temperatures every time, you remove variables, and removing variables is what lets you actually learn your starter and your dough. Once you know that your levain peaks in 4 hours at 26 degrees, or that your bulk fermentation finishes in 8 hours at 24 degrees, you stop guessing and start planning. That is the difference between sourdough feeling like a stressful science experiment and sourdough feeling like a reliable part of your weekly routine.