September has arrived, but it’s still really hot across South Texas. Afternoon temperatures in San Antonio reached the upper 90s on Tuesday, and they are expected to climb close to 100 degrees through the rest of the week, while humidity-driven heat index values could approach 105 degrees or higher.
Despite the summer-like heat, Tuesday marked the first day of meteorological fall. That’s different from the traditional start of fall, which doesn’t arrive until the autumnal equinox on Sept. 22.
So why do meteorologists use a different start to the seasons? First, the traditional start to the seasons vary slightly from year to year, which can mean inconsistent data comparisons. To make things simpler, meteorologists instead use fixed dates: fall begins Sept. 1, winter Dec. 1, spring March 1 and summer June 1…