Temperature reference
36–40°F Sourdough (2.20–4.40°C)
Bulk multiplier: 10.000× · Proof multiplier: 10.000× · Activity: dormant
Dial shows where 36–40°F sits on the sourdough activity scale (32–100°F). Indicator points at the midpoint; color shifts from cool blue (dormant) to warm orange (hyperactive).
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:
- Country Loaf (Pain de Campagne)
- Ciabatta
- Baguette
- Focaccia
- Sourdough Brioche
- 100% Rye Pan Loaf
- 40% Rye Hearth Loaf
- 100% Whole Wheat Pan Loaf
- Spelt Hearth Loaf
- Pain de Campagne (Variant with Rye)
- Sourdough Bagel
- Sourdough Pretzel
- Neapolitan Pizza (Sourdough)
- NY Style Pizza (Sourdough)
- Focaccia Genovese
- Pain au Levain
- Miche (Poilâne-Style)
- Pan de Cristal
- Ciabatta Integrale
- Sourdough English Muffin
- Sourdough Naan
- Sourdough Tortilla
- Sourdough Challah
- Sourdough Panettone
- Hokkaido Milk Bread (Sourdough)
Related references on this site
- Guide: temperature and time in sourdough — the piecewise-linear multipliers and how to use them in planning
- Autolyse strategy by temperature — warmer kitchen needs shorter autolyse before adding starter
- Levain build timing — how long to wait before peak in a hot vs cold kitchen
- All 25 recipes — each has a /timing page — each recipe shows bulk + proof at 36-40°F
- All 12 hydration levels — drier doughs ferment slower; combine hydration choice with temperature
- All 8 temperature ranges — from cold retard 38-40°F to peak summer 88-95°F