Temperature - how low is to low?

Caudery · May 20, 2015

I live in a cold area and its gets down to 4 Celsius (I think thats 40 fahrenheit) will the effect the beer to much during fermentation?

azazel1024 · May 20, 2015

Yes. Lagers can be fermented between about 48-56F and Ales between about 58-74F. Depends heavily on the specific strain of yeast and slight exceptions exist where the lager or ale yeast will behave will a little warmer or colder (some ale yeasts are 65-72F only, some might handle as warm as 80F, some as cold as 58F, etc.)

At 40F even lager yeasts are going to go dormant and not ferment. You'll have to find a way to keep the wort warmer than that or else the yeast will not ferment it. Heating pad and a blanket is a cheap and quick way to do that.

Caudery · May 21, 2015

How much will it effect the beer if every night it goes to 40F and then goes up 55F-70F during the day?

snow16 · May 21, 2015

It will effect your beer greatly. As mentioned above, you absolutely need a way to heat your fermenting beer. Another way to do it is with an inexpensive aquarium heater and a trash can. Works wonders.

azazel1024 · May 21, 2015

If the actual temperature of the beer drops more than about 2-4F below the low end of the yeast strain, it'll likely go dormant. You'll get some nasty, nasty beer as a most likely result if it is during very active fermentation. Those are the times I see brewers end up with sour apple flavors and that sort of thing.

You must keep it within a few degrees on the top or bottom end of the recommended temperature range otherwise you'll tend to get off flavors.

If the ambient temp is cycling as low as 40F, it doesn't matter how active the fermentation was, it'll conk out the yeast. Temperature variability isn't the worst thing ever, but BIG swings means you are not likely to produce drinkable beer (or produce beer at all).

Bamsdealer · May 21, 2015

my advice is to get one of those rope handled Rubbermaid tubs and fill it halfway with water. get it off the ground by putting a few boards underneath, put your fermenter in and cover it with an old comforter or sleeping bag. I ill bet your beer doesn't swing more than a few degrees over the course of a day.