While I don't doubt that cooling the lnb could help a bit, one thing that hasn't been mentioned is that when the temperature drifts much from "normal" ambient temperatures, most of the lnbs we use will drift in freq. I had one KUL1 lnbf that drifted 5 MHz off freq when the temperature got down to mild winter temperatures. Other low cost Cal-Amp and Norsat LNBs would drift up to a couple MHz. I now have a couple more stable lnbs, so I'll be interested in how much they drift this winter, but the bottom line is that all these lnbs are rated over a relatively narrow temperature range.
Similar to the ICE example above, I once had an LNB that when the temperature got down into the 10-15 deg F range, it would develop an internal oscillation that you could see going across the band. As the temp dropped each night and went through that 15-10 deg range, you could see the birdie signal destroy one channel at a time. I had to put an X-10 switch on the receiver, and when the oscillations started, I'd switch it off for a few seconds, then turn it back on, and it would be OK. Once the temp got below 10, it was OK.
I have generally had better reception in winter, but I attribute that to having no leaves on the trees.