In my hardcore modpack I kept creating worlds where it was winter. The temperatures and ice were making it very difficult, so I tried to change it to LAN with cheats on, and use the setseason command, but when I do that it seems to reload everything, the season sensor for winter turns off for a second, but then turns back on and nothing's changed at all. I took it off hardcore and just made a creative world with cheats on by default, and I still can't change the season from winter.

after looking at config files, it might be the russian mod I'm using to make days three times as long

it might be starting worlds in january only, and thus mid-winter and not responding to the /ss setseason command

yup, that did the trick