I'm brewing two batches of grain mash, since im using a small pot.

Anyways, half is cooling outside right now, the other half is on the stove, I plan to combine the two afterwards then get it to 70°F to add the yeast.

How cold can the half outside get? It's -30°F (-34°C) outside (no yeast is added yet).

1 Answer 1


I suppose you want to know how cold does it need to be, so that once it is combined with the other half, you get 70°F ?

It depends on how hot is the wort on the stove, once you know that temperature, you can calculate it based on the volume. In any case, you can't let it freeze or it will be hard to transfer.

If one half is close to the freezing point and the other is close to the boiling point, once mixed you will be in between (about 122°F). You might need to bring it back outside to get to 70°F.

  • Would it be okay if the mash gets too cold? For example if left too long, will being frozen hurt the mash (Keeping in mind no yeast is added at this point)
    – dustytrash
    Commented Dec 10, 2019 at 16:54
  • Just bring it back to the correct temperature before adding yeast and it will be fine. It is more important to cool it quickly to avoid contamination, but I don't think too cold will be a problem, if you bring it back to correct temperature quickly and add the yeast.
    – Philippe
    Commented Dec 10, 2019 at 17:35

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