JACKSONVILLE, Fla. — It's another hot day here on the First Coast, despite the fact that Sunday marks the beginning of meteorological autumn.
You might be thinking, "Wait a minute, isn’t autumn supposed to start in late September?" And you're right—at least according to the astronomical calendar. The official start of astronomical autumn is marked by the autumnal equinox, which typically falls around Sept. 22 or 23.
What’s the Difference Between Meteorological and Astronomical Autumn?
The difference lies in how the seasons are defined. Astronomical autumn is based on the Earth’s position relative to the sun. The autumnal equinox occurs when the sun crosses the celestial equator, resulting in nearly equal amounts of daylight and darkness—about 12 hours each—across the globe. This event marks the official start of autumn in the astronomical sense.
Meteorological autumn, on the other hand, is based on the annual temperature cycle and is used primarily for record-keeping and statistical purposes. It aligns more closely with our weather patterns and is divided into three-month blocks. Meteorological autumn runs from Sept. 1 to Nov. 30, followed by meteorological winter from Dec. 1 to the end of February. This method allows meteorologists to compare weather data more consistently across years.
A Local Perspective on Meteorological Autumn
Here on the First Coast and in Jacksonville, it might not feel like autumn yet, even though the meteorological calendar says it is. Temperatures are still soaring into the 90s, far from the cooler weather we associate with fall. Personally, I’d like to propose that the start of meteorological autumn for our area should be Oct. 20. On this date, the average high temperature is 80 degrees, and the average low is around 60 degrees, which feels more like the crisp, cool weather we expect in autumn.
Regardless cooler weather will come eventually. For more on the local forecast please visit here.
