The weather and seasons
On Howrse, the seasons last one week. Fall starts on the first day of each real month. Since each season lasts 1 week, Winter begins on the 8th, Spring arrives on the 15th, and Summer starts on the 22nd. Summer lasts until the end of the real month, then the cycle of seasons starts again the next month.
In-game seasons have an impact on the amount of grass in meadows. There is a lot of grass in fertile meadows during the Spring and Summer, but it gets scarce in winter.