I pitched English Ale yeast (white labs) around 80 deg, not realizing it was that warm. Relative temp in the room is 68, but wort will not cool down below 80....strange! Its been about 24 hours at 80deg. Yeast has been in wort for 5.5hr

Should I be worried about the temp of the wort, and should I try to re-pitch more ale yeast if no head or CO2 kicks up?

3 Answers 3


Should you be worried? Yes and no. That temp is not high enough to hurt the yeast, so if it hasn't started fermenting yet it will soon. But that temp is WAY too high to make good beer. The usual effects are lots of fruity esters and fusel alcohols. Neither of which make for a pleasant beer drinking experience. At this point you can try to cool it down and see what happens.


Your wort is probably reading 80 degrees, when the rest of the room is 68, at least in part because fermentation is exothermic. I don't know whether that would explain all 12 degrees of difference, but you should expect your wort to be warmer than ambient temperature.

That said, I think you should follow Denny's recommendation and attempt to cool the wort.

  • 1
    If the yeast has only been in the wort 5.5 hours, then its not fermentation that's causing the heat.
    – GHP
    Jul 16, 2013 at 12:12
  • Correct. There is so much thermal mass from the liquid that the room temp is hardly an effect on the beer.
    – Denny Conn
    Jul 16, 2013 at 15:57
  • Yeah, I remember being surprised by how slowly 5gal of wort heats up or cools off to room temp when I started brewing. 12 degrees above ambient can happen during active fermentation, but it usually takes a day or two of heavy activity before it builds that high.
    – GHP
    Jul 17, 2013 at 14:12

For bread making and other uses of yeast "blood heat" is used. That is, a temperature at the same temp as body temperature. So not a problem for the yeast. Pitching warm for an hour or two may help the yeast propagate quickly. But it'll make some strange nasty flavors.

Ale temperature needs to be about five degrees less (about 68 give or take a few degrees) and lager much less (50). If your fermenter is a glass carboy or something like that you can dunk it in a clean trash can or bath tub full of ice water to get the temp down. Aim for two or three degrees cooler than your target and then pull it out and put it in a cool dark place away from the light. Like a closet. If you keep your house at 68. It should be ok for ale as the fermentation will bring it back up a few degrees.

Check for fermentation signs with in 24 to 48 hours and if there are signs then you won't need to re-pitch your yeast.

  • 2
    Those temperatures (72 for ale, 65 for lager) are higher than recommended. Although most ale yeasts specify a temperature range up to 70 F., you'll make much better beer if you keep the temperature near the bottom of the range -- closer to 60 F. Lager yeasts vary in their recommended temperatures, but 55 F. is about the highest you could get away with. 65 F. is much too high for any lager yeast except for California common. Jul 16, 2013 at 15:46
  • Celsius to Ferenhiet calculation error. Jul 17, 2013 at 4:14

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