winemaking temperature

What is the optimum temperature for making wine, I believe it is normally 60-7 degrees but I am wondering how low the must can get before a problem is created. Is 40 F too low? I have my primary out in the garage now and it may get down to 40F this week. After the initial vigorous fermentation I will bring it inside and it won't be a problem. Should I wrap the bucket or something? Thanks

Wine likes to be a bit warmer than ale, but check the yeast package to make sure. Some wine yeasts do ok up to 80 degrees. Wine yeasts tend to have a more forgiving temperature range than ale yeasts. Check this chart to be sure:

http://www.wyeastlab.com/winery/wi_temp&res_sugar.htm

But, 40 degrees is way too low no matter what yeast you are using. That is called cold crashing, and will cause the yeast to flocculate out and the wine to clear. That's ok, if the wine is fermented to dry already. But, anything under 60 degrees will be harmful if you're hoping to have some fermentation with that wine now or in the future. You can also get wine crystals from that low temperature, when tartaric acid (I think!) settles out because of the low temperature.

I keep all my wines in my house until bottled, then they go into the basement. The coldest my wine cellar/pantry ever gets is 40, in the winter. The rest of the year it's about 55 degrees.