Lower temps affect attenuation?

All my fermenters sit in my basement which is usually in the 60-65 range. The last two batchs I did, seemed to be a little low on the attenuation side.

First one was a stout extract OG 1.079 and FG 1.033 with White labs Irish Ale
Second was an apricot wheat OG 1.046 and FG 1.013 with Safale US-05

The apricot wheat isn't to bad for att. but the stout seems low. It was definately done fermenting..

Hi,
As long as you are fermenting within the recommended range for the yeast, you should not see a significant difference in attenuation.

More likely the attenuation variations are a result of ingredients, mash schedule, etc...

Also - using a properly size yeast starter is very important.

Cheers!
Brad

When fermented at the lower end of a yeast's range (which is not necessarily what the yeast companies claim), yeast become very sensitive to drops in temperature. A drop of only a few degrees, particularly towards the end of fermentation, can cause the yeast to drop out and not finish. It is a good idea to ramp up the temp of fermentation as it progresses, particularly if you are fermenting cold, in order to ensure that the yeast finish fermenting and clean up after themselves.