Going from August to September can be a little confusing sometimes. Usually because when someone says “It’s finally fall”, there’s someone else that says “Well, it’s technically still summer”. Actually, both are right. Meteorological and astronomical fall are two ways we track the change from summer to fall.
Meteorological fall always starts on September 1st. The meteorological seasons are the 3 warmest months, the 3 coldest months, and the 6 transition months that are in between. So out of those 6 transition months we have meteorological fall or September, October, and November. Because the grouping of months is based on the annual temperature cycle, this makes it a lot easier to conduct seasonal comparisons like average temperatures, average precipitation, etc.
Astronomical fall is based on the earth’s orbit around the sun and the earth’s tilt. This is also how we get all of our seasons. This year it falls on Tuesday, September 22nd. On this day there will be an equal amount of daylight and darkness due to the sun being directly over the equator. Due to leap years, the day that any astronomical season starts does vary. This is why the meteorological standard is used to collect data that’s always even across 3 month increments. But if you want to be more precise when it comes to to the official start of fall, then the astronomical standard is your go-to.
The month of September doesn’t only bring a switch from summer to fall, but a drastic drop in our high temperatures. The month gets started on a toasty note with average highs in the upper 80s but then they’ll fall into the upper 70s by the end of the month.