Before we look ahead into September, we take a look at weather stats for the month of August. For an NWS climate reporting station central to our viewing area and best representative of everyone, we have the Northwest Alabama Regional Airport in Muscle Shoals. For a large part of the month of August, temperatures came in roughly about normal. The hotter periods came in short bursts around mid month and then this past weekend when we had short periods of above average temperatures. While a large part of the month was near average for overnight temperatures as well, there were a few different overnights with below average temps, mainly due to either rain-cooled air or temporary bursts of drier air allowing for more efficient radiational cooling behind weak frontal boundaries. The month came in with 3.79 inches of rainfall, right around normal.
September begins the very early stages of changes heading into fall, especially by later in the month. The sun angle starts getting lower, and we lose nearly an hour of daylight on average through the month. We are typically still on the warm side, but the average daytime high is on the way down as we head through the month. Our average monthly high for September comes in around 86 degrees, but that begins at 89 on September 1st and is around 79 as we head out of September and begin October. Our monthly average low is around 63 degrees, with that beginning around 68 at the start of the month and 58 by the end of the month. We can certainly be hot this time of year though. The record monthly high for September was 108 set in 1925. We can also start to catch an overnight chill occasionally too, though we stay above freezing. Our record monthly low is 36 degrees, set in 1901. While it’s not always the case, September is often one of the drier months of the year here in the Tennessee Valley, along with October. It usually takes a tropical system to cause that to not be the case. Our area averages roughly 3.55″ of precipitation for the month of September.
Severe weather is very infrequently a concern during the month of September, but it can occasionally happen. While we can still see a pop-up summer storm with damaging straight-line winds, they are becoming less frequent, and we are becoming less likely to see summertime thunderstorm complexes with organized wind damage threats. Tornadoes are usually only a problem when we are dealing with the remnants of a landfalling tropical system, and we have a small number of them on record here in our local area. But they do happen. VERY OCCASIONALLY, we can see a jet stream/frontal system during the latter part of the month that has enough wind shear for an organized tornado threat, but that is a pretty rare circumstance.
We do definitely have to keep an eye on the tropics in the month of September. This is actually, historically, the most active time of the year for the Atlantic hurricane basin. The statistical peak of the Atlantic hurricane season falls on September 10th. We have to keep an eye for locally developing systems in the Gulf and Caribbean, as well as long-tracking systems from out in the Cabo Verde tropical waves that roll off the coast of Africa. Both can be a significant threat to the northern Gulf Coast this time of year, and some very notable hurricanes in history have made landfall during the month of September. We’re not ALWAYS active though, and this may be one of those years that we are not because of the very strong El Nino already in place, but we still have to watch things carefully. All it takes is one storm to cause big problems!