A new season has begun, at least in the meteorological world. September, October and November are categorized as the “autumn” months even though much of this month still is summer by astronomical standards as denoted on our calendar. In any case, it’ll feel a lot more like summer than fall for the next week. In fact, it may feel a lot more like summer than much of the month of August! Three weeks of the past month had below-normal temperatures as the August’s average temperature came in ~3° below normal. A few rainy spells and a persistent trough in the jet stream over the Midwest were to thank for much of that.
As we head into September, the weather pattern is initially quite a bit different. We’ve got a sprawling ridge of high pressure over the eastern 2/3 of the U.S. that is keeping any cooler air intrusion at bay. At the same time, the ridge isn’t overly strong so the worst of the heat also isn’t showing up. What this means for us in Oklahoma is typical summertime weather with little trigger for rain and temperatures that are increasingly above normal, mainly because our average temperatures start to drop off quite a bit this time of year. Our average high temperature here early in September is 90°. By month’s end, that average high is just 78°! That transition to fall weather isn’t far off now.
At least through Labor Day weekend however, we’ve got 90s for highs and 70s for lows with lots of sunshine each day. That is quintessential summer weather for Oklahoma, which means traditional Labor Day activities at lakes, pools and campgrounds should be largely uninhibited by bad or unseasonably cool weather. That said, a pattern change is showing up next week. A weak cold front may enter our state as early as Labor Day itself, bringing rain and storm chances along with refreshing air. This is not a big change, but should level us out to near-normal temperatures by then with highs more commonly in the 80s than 90s.
In fact, as we look all the way out for the rest of the month, temperatures may be near to slightly warmer than normal overall, but rainfall may increase to above-normal levels. After this dry spell, some wet weather won’t be unwelcome. The attached outlook maps show above-normal temperatures for much of the area in September with above-normal rainfall possible as well.
We are now in the Atlantic basin’s most active month for hurricanes, and fortunately, the U.S. mainland has lucked out without any significant issues from the now fully-decayed Tropical Storm Erika. In case you wondered what happened to Erika, the storm went over a few land masses that starved it of energy as wind shear tore the storm apart. Another hurricane named Fred formed not far from the coast of Africa, but it’s incredibly eastern position in the Atlantic has precluded any risk for us. In fact, that hurricane was the first to strike the Cape Verde islands in over 100 years! Meanwhile, the Pacific Ocean has three major hurricanes on its hands, but none are posing a major threat to land. (See third map)
Enjoy our string of persistently muggy days. Fall-lovers, while cooler air isn’t immediately showing up, you can be assured that the days with 90° to 100° temperatures will soon be a rarity!