Weather Blog: Saying hello to autumn

By Jamie Martin, Meteorologist
Last Updated: Wednesday, September 21, 2016, 6:59 AM EDT

As we start the first official day of fall on Thursday, Sept. 22, at 10:21 a.m. eastern time, I thought it would be a good time to remind people about what the autumnal equinox is all about.

The word equinox comes from the Latin words "equi," meaning "equal" and "nox," which means "night." It refers to the moment when the sun crosses the equator, which more or less brings an equal amount of daylight and darkness here on earth that day.

The equinox happens two times each year, once in the spring and once in the fall. You need to remember one thing though. In the Northern Hemisphere it marks the beginning of fall. In the Southern Hemisphere, it marks the beginning of spring. And vice-versa in March. While we are baking in summer heat, they are skiing on snow in parts of South America.

You may have heard that the meteorological summer ended on Aug. 30. The reason it is not linked to the equinox is that it makes it more precise to gather and analyze data for the specific season. The problem is that the astronomical season start dates vary year to year. Of course, we know fall doesn’t really start until November here in Central Florida!

Remember that gorgeous moon last week? That was the Harvest Moon. It is the full moon closest to the September equinox and it happened on Sept. 16. The last time the Harvest Moon was on the actual autumnal equinox was in 2010 and this won't happen again until 2029.

So get out and celebrate the autumnal equinox, even though we will see highs near 90!