No matter whether you go by the astronomical calendar or the meteorological calendar, both agree that the country has now entered fall.
The autumnal equinox officially occurred on Monday at 2:19 p.m., when Earth’s alignment allowed the Sun to be directly over the equator. This marks the point of the year when there are roughly equal amounts of daylight and darkness.
For the Northern Hemisphere, however, daylight hours are now on a steady decline as the region heads toward winter.
In addition to the shrinking daylight, temperatures also see their biggest drops of the year.
For instance, along the Interstate 10 corridor in the northern part of the state, average highs usually reach the mid to upper 80s in late September but plummet to the mid to upper 60s during the final weeks of astronomical fall.
Further south along the Interstate 4 corridor, daily highs typically start near 90 degrees Fahrenheit at the beginning of the season before sliding into the more comfortable mid-70s by its end.
In South Florida, upper 80s dominate early on but steadily fall to the upper 70s to near 80 degrees as astronomical fall wraps up.
It is also the time of year when the first frost and freeze typically occur in the Panhandle and parts of Northeast Florida.
In recent decades, however, those first dates have been arriving later than normal, with impactful cold snaps now more common in December and January.
Meteorologists and climatologists officially define autumn as the full months of September, October and November.
According to NOAA, using these three-month blocks for each season makes it easier to compare records and analyze long-term climate data, rather than adjusting dates each year based on the astronomical calendar.
Whichever calendar system you follow, Mother Nature’s version of fall will feel anything but autumn-like in the days ahead.
Back to summer-like regime
For most of the state, the start of astronomical fall will be met with temperatures running 5 to 10 degrees above average.
An easterly to southerly flow is allowing temperatures to feel more summer-like, with temperatures well into the 80s and 90s.
Tuesday and Wednesday appear to height of the fall heat wave with heat indices that could reach near 100 degrees along the Interstate 10 corridor.
There are generally two ways that kind of heat can break - either a cold front or a tropical system. Neither of which are expected to impact the state over the next few days, meaning the warm pattern will linger for a while.
NOAA’s climate outlook also called for the season to be both warmer and wetter than average, but so far that hasn’t been the case for communities north of Interstate 4.
Instead, drought conditions are beginning to emerge in cities such as Gainesville, Tallahassee, and Jacksonville, and will likely intensify until significant precipitation arrives.
Unlike the northern half of the state, parts of South Florida have been contending with storm impacts that brought widespread rainfall and flooding. Fort Lauderdale has reported more than 5 inches of rain since the start of the month, while Miami has seen nearly 16 inches of precipitation.
Wet weather chances look to remain in the extended forecast for South Florida, which could lead to isolated flooding concerns.
