Cold air is more dense than warm air. This will cause your patterns to open up more, meaning they will not be as tight as they will be in warmer conditions. As far as what temp to pattern in, I'd try to pattern in temps that are likely to be avg during turkey season. Down here, temps can range from 30-80 degrees, so its kinda hard for me to narrow it down. Just keep in mind that if you get a killin pattern at 40 yds with warmer temps, it will be more open on cold mornins. JMO. Hope this helps.
