I thought I would post this seeing as I've seen a few people who are wondering when the seasons change, this guide is from AC:WW but I assume it's the same seeing as the stuff that's happened already has been the same, if it's not then please post so I can correct it.
- February 17th - The trees still have snow on them but they turn green.
- February 24th - Snow season ends.
- February 24th - Snowball season ends.
- February 25th - First day of Spring and everything is a yellow green.
- April 1st - The trees will have pink blossoms
- April 8th - The blossoms will end and the ground and trees will be darker green.
- June 1st - Rainy season begins.
- June 1st - Thunderstorm season begins
- July 15th - Rainy season ends.
- July 23rd - Grass becomes brighter and trees become a bluish green.
- September 15th - Thunderstorm season ends.
- September 15th - Tanning season ends.
- September 16th - First day of Autumn and everything looks as it did February 25th.
- Autumn (don't know exact dates) - Rumored to be the dry season.
- October 1st - Grass changes to a yellowish color and some trees turn more yellow.
- October 16th - Grass and trees turn more yellow
- October 22nd - Grass turns yellow-orange and some trees are yellow-orange & gold.
- October 26th - Some trees turn more orange and the grass is pretty much the same.
- November 4th - The trees are now scarlet, gold, and yellow-green colored.
- November 10th- Trees are orange and red, grass is still the same.
- November 12th - Snow season begins.
- November 12th - Snowball season begins.
- November 19th - Trees are red, maroon, and orange, grass is brown with blue spots.
- November 20th - Trees are a redish purple and brown.
- November 26th - Grass is the same color, although without the blue spots.
- December 10th - Nothing happens, except it is guaranteed to snow this day.
- December 11th - The snow sticks to the ground and trees will be covered in snow.
