Dough Temperature
Temperature is the single most important variable in bread baking. It controls fermentation speed, which controls how long bulk fermentation takes, how much flavor develops, and whether the dough overproofs or underproofs.
A dough that's 5°F warmer than expected will finish bulk fermentation hours earlier. A dough that's 5°F cooler will take hours longer. Recipes that say "4–6 hours" are assuming a specific temperature range. If your kitchen is different, your timing will be different.
The ideal final dough temperature (FDT) for most sourdough is 75–78°F (24–26°C). At this temperature, bulk fermentation takes 4–6 hours and produces good flavor without overproofing.
Measure dough temperature with an instant-read thermometer immediately after mixing. If it's too warm, use cooler water next time. If it's too cold, use warmer water.
Water temperature is the one variable you can control precisely before mixing. The formula:
Friction factor is typically 0–2°F for hand mixing. For most home bakers, a simpler approach: if your kitchen is 68°F, use 80°F water. If your kitchen is 75°F, use 70°F water. Adjust from there based on results.