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Prepare for near 90 degree weather

By Skip Rigney
The last time it was undeniably hot was back during the first week of October when afternoon highs reached the middle 90s six days in a row.
It won’t be that hot anytime soon, but some of us may reach the 90 degree mark for the first time this spring on Monday or Tuesday as high pressure along the northern Gulf Coast and the increasing strength of May sunshine warm us up. That will be quite the change from the cooler-than-normal mornings this past week when low temperatures fell into the upper 40s.
Making a big deal out of the first day that we break 90 degrees is something of an arbitrary game. After all, it’s just one degree warmer than 89 degrees and one degree cooler than 91. That’s much different than the first freeze of the season. A degree or two above or below the 32-degree mark can make a big difference to tender plants.
But, 90 degrees is a nice round number, and our first encounter with that number during the year is a good reminder that we’ve probably entered late spring, and summer is just around the corner.
The median date for first reaching 90 degrees in Poplarville is May 19th, based on 89 years of historical weather data at the Poplarville Experiment Station. That means that for fifty percent of the years on record, the first occurrence of 90 degrees during the year was between April 11th (the earliest it’s happened, which was in 1963) and May 19th. The other fifty percent of the years on record, the temperature didn’t reach 90 degrees until between May 19th and June 15th (the latest first occurence, which was in 2017).
So, if we do make it to 90 degrees on Monday or Tuesday, that degree of warmth will have arrived ahead of schedule this year. But, the long historical weather record at Poplarville shows that it’s certainly been into the 90s this early before, in fact, it’s happened this early about 25 percent of the years on record.
Although forecasters expect us to be near the 90 degree mark Monday and Tuesday afternoons, it’s far from a certainty that every location in the county will actually reach 90. In their forecast discussion a couple of days ago, the National Weather Service in Slidell put it this way: “Not overly confident in temperatures this warm. However, any subtle ridging (of high pressure) in early May usually doesn’t take much for us to crack 90 degrees along the northern Gulf coast. But the difference between 88 and 90 is basically negligible, so the main story will be increased afternoon heat.”
A cool front is forecast to pass through on Wednesday. The air behind the front will be much drier. Not only will that make it feel less muggy, it will allow overnight and early morning temperatures for Thursday through next weekend to drop back to near 60 and perhaps into the upper 50s. Bright May sunshine will allow our afternoon highs on those days to climb into the 80s, but the threat of 90s will be gone for a while.