In one-shot games (which, unfortunately, is most of what we play, these dyas), if I am the GM, I will throw it in whenever I think it's convenient, but that's rarely. Most adventures take place in a few weeks, or less.
In campaigns, I am famous (infamous?) for bedevilling the PCs with minor, mundane stuff... like weather. First level PCs who adventure without tents soon learn why they are important! Those without bedrolls & blankets suffer fatigue, etc.
In a campaign, I will announce the time of year at the outset, and have the weather pre-rolled for two weeks at the start of the campaign. If the PCs go on a long trip that takes up more than two weeks, I will make up the rest, instead of stopping to roll, then roll up another month or so after the game.
In one subtropical campaign, I had a platemailed PC running around the jungle, and constatly had him rolling for heat exhaustion, but somehow he just never seemed to fails his roll!
In another winter campaign, I had a dextrous Wylf (Elf) go out, early one frosty morn, to go check on the horses, hit the icy, second-story steps... and recover admirably, without swan-diving to the bottom!
Lucky PCs, I tellya!
I also did a MERP Campaign wherein the PCs spent Christmas in Bree, and had to come up with presents, and contributions to the Yuletide Feast... No combat, but some fun roleplaying, as I recall! Good times!...