Temperature reference

36–40°F Sourdough (2.20–4.40°C)

Bulk multiplier: 10.000× · Proof multiplier: 10.000× · Activity: dormant

Recommendation

Refrigerator territory — used for overnight retard during proofing or bulk slowdown. 12-16 hours at this temperature is equivalent to 1-1.5 hours at 76°F baseline. Essential for flavor development in artisan sourdough. Cold retard improves shape retention, enables flexible scheduling, and develops deeper tangy flavors. Place dough in floured banneton, cover, refrigerate at this temperature.

Timing calculator at this temperature

Multiplier at 38°F
2.9×
Adjusted bulk ferment
11.6 h
Adjusted final proof
34.8 h
How the math works

Multipliers are piecewise-linear interpolations between reference points measured by Myhrvold et al. in Modernist Bread vol 3. 76°F is the baseline (1.0×); every 10°F drop roughly doubles fermentation time, and every 10°F rise roughly halves it.

How each style behaves at this temperature

Click any style to see its full timing at 36–40°F: