Depending on where they go on the World Map of Aloria different worlds would have different seasons and timings. Here's how I see it:
Month: June/Summer Season
Ellador - Days Really Long, Nights Really Short. Snow retracts northward (if possible to code). (northern hemi)
Ithania - Days Long, Nights Short (norther hemi)
Deandroc - Days and Nights are not affected.
Regalia - Days and Nights not affected.
Kelmoria - Nights Long, Days Short (southern hemi)
Farradeen - Nights Long, Days Short (southern hemi)
Jorrhidr - Nights Really Long, Days Really Short (southern hemi/pole)
All instances unaffected (all are located near the Regalia and Silverwind, aka, near the equator).
New worlds get day/night cycles in a similar manner - this would help with creating world maps because you could tell how north or south something is by the length of its days.
I envision each MC month as being 15 days long and each season being as follows:
North/South Pole - Summer 6 months/90 days, Winter 6 months/90 Days
North/South Hemi - Summer 4 months, fall 2 months, winter 4 months, spring 2 months. 4 months = 60 days, 2 months = 30 days.
Equator - No Seasons, No Change in Day/Night Cycle or Weather Patterns.
Weather during the seasons would be as follows:
Summer - Standard Rain, Crops Grow 3/4ths rate if not within 2 blocks of water.
Fall - Less Rain, Crops Grow Standard Rate.
Winter - Rain becomes snow across all Northern Hemi and Southern Hemi worlds. Standard Rate of Rain/Snow. Crops grow 1/4th Rate overall.
Spring - Snow becomes Rain across all Norther and Souther Hemi worlds. More Rain/Snow. Crops Grow Double Rate overall.
Note on Seasons: Summer = Hot Season, Winter = Cold Season, Fall = Dry Season, Spring = Wet Season. They are inversed between Northern and Southern Hemi worlds.