Summer Sourdough Crushed Ice & Water Temp Chart for a Hot 90 Degree (90°F / 32°C) Kitchen — Hand Mixing (75°F Target DDT)
4-factor Desired Dough Temperature (DDT) and 80 cal/g latent heat crushed-ice calculation for hitting 75°F dough in a hot 90°F room.
Target a 75°F (23.9°C) dough, account for a 90 degrees (32.2°C) room plus 90 degrees flour and levain, then add the +2°F of heat that hand mixing (75°f target ddt) generates: 4 × 75°F − (90 + 90 + 90 + 2) = 28°F of mix water. Blending 92g of crushed ice with 258g of 78°F water is how you reach 28°F in this kitchen; the phase change alone strips 80 cal per gram before the water even warms.
- Required Water Temp
- 28°F (-2.2°C)To hit 75°F DDT in 90°F room
- 350g Batch Ice Split
- 92g Ice / 258g WBased on 78°F tap water & 80 cal/g latent heat
- Mixer Friction Factor
- +2°FHand Mixing
- Target Final Dough Temp
- 75°F (23.9°C)Locks fermentation clock & protease rate
Batch-Scaled Ice & Water Chart for a 90°F Kitchen (Hand Mixing (75°F Target DDT))
Read the ice column as a direct instruction: weigh that much crushed ice and make up the balance with 78°F tap water.
| Total Water | Calculated Temp | Ice Quantity | Tap Water Quantity | Dough Temp Target |
|---|---|---|---|---|
| Line 300g [Exact Target] | required 28°F (-2.2°C) | weigh 79g ice | measure 221g liquid | expect 75°F dough |
| Line 350g Alt Line A | required 28°F (-2.2°C) | weigh 92g ice | measure 258g liquid | expect 75°F dough |
| Line 500g Alt Line B | required 28°F (-2.2°C) | weigh 132g ice | measure 368g liquid | expect 75°F dough |
| Line 250g Alt Line C | required 28°F (-2.2°C) | weigh 66g ice | measure 184g liquid | expect 75°F dough |
| Line 400g Alt Line D | required 28°F (-2.2°C) | weigh 105g ice | measure 295g liquid | expect 75°F dough |
Dynamic Stoichiometric Workbench (28°F (-2.2°C))
Test custom loaf weights or alternative fermentation schedules directly against the 92g Ice / 258g W benchmark above.
Baking Sourdough in a Hot 90°F Room: Why You Need 28°F Water (92g Ice)
The Desired Dough Temperature equation treats the dough as a single thermal mass with four contributions. For this 90 deg F (32.2°C) kitchen, three of them — room, flour and levain — are each 90 deg F, and the fourth is the +2°F that hand mixing (75°f target ddt) adds through shear. Solving for the water temperature is the only way to hit 75°F exactly.
The recipe's own water temperature is not the mix water temperature. If your recipe specifies water at 32.2°C because it was written for a 68°F kitchen, that number has to be re-solved for this 32.2°C (32.2°C) room and for the +2°F that hand mixing (75°f target ddt) generates.
Thermal Control Protocol for Hand Mixing (75°F Target DDT) in a 90°F Room
- Probe Ingredients (90°F / 32.2°C): Verify ambient room (90°F), flour, and starter temperatures with an instant-read probe thermometer before running Hand Mixing (75°F Target DDT).
- Weigh 92g Ice + 258g Tap Water: For 350g total water, combine 92g finely crushed ice with 258g (@ 78°F) tap water.
- Verify Final 75°F Dough Temp: Probe the dough center immediately after hand mixing (+2°F friction); it should read 75°F ± 1°F.
- Record the Reading: Write the actual temperature on your recipe card — in a 32.2°C (90°F) room the next bake will need the same correction, not a fresh guess.
Key Baker's Math Questions (Required Water Temp: 28°F (-2.2°C))
Does humidity in a 32.2°C (32.2°C) kitchen change the water temperature?
Marginally. On a humid morning the dough surface loses less moisture and cools a little less, so half a degree less cold water is usually right. Treat it as a refinement, not a correction.
Will the dough temperature change if I scale the recipe?
No. The 4-factor equation is a temperature balance, not a mass balance, so doubling the flour and water keeps the same 28°F target — but you must double the ice too, from 92g to 184g.
Why does my dough come out warmer than 75°F in a 90°F room?
Almost always the friction term. If you used 78°F faucet water instead of 28°F, the 2°F that hand mixing (75°f target ddt) generates has nowhere to go, and the finished dough overshoots the target.