Berks weather in July: hot and confusing

Last month broke the mold in Berks County: An average temperature tied for sixth hottest on record with comparatively few 90-degree days.

“I cannot think of any good analog for this July’s temperature trends,” said Jeffrey R. Stoudt, a retired meteorologist and Berks weather historian. “The key is that it (was) consistent and persistent with low to moderate heat. There have been no large departures either side of normal. Departures on the cool side have been few and small. Even the 97s (two days that were the hottest of the month) would be considered modest when compared to typical July month maxima over the decades.”

Last month ended at an average temperature of 79 degrees at Reading Regional Airport, the National Weather Service site in Berks, which has been there since February 1999. The temperature record period begins with 1898.

That 79 was a tie for sixth with 1952 and 1999.

There were only 12 90-degree days in July, which is three fewer than any other month among the 10 hottest, and further down the list July 1999 had 20 90-degree days and July 1952 had 17 90-degree days. But both also had more offsetting chills.

The 90s mainly came in clumps last month, with a three-day heat wave and later a seven-day heat wave. A heat wave is commonly considered three straight days of at least 90 degrees.

All the daily high temperatures last month reached at least 81 degrees.

Stoudt was on the case.

“I investigated the status of all 31 days of July warming to at least 80,” he said. “I was surprised that none of those from the midcentury warm decades made it. A few had one miss, a 79. A few more had one miss, a 78. … Even a whole month of July, 31 days, proved to be too long to go without a thickly cloudy day when temps were held down or a strong incursion of relief from the far north.”

“Finally, July 2011 had all 31 days warm to at least 80, the coolest daily high of 84,” said Stoudt, also the founder of the Berks Area Rainfall Networks. “Even later, July 2020 was one of those one-miss-79 of a July.”

The bigger picture

The 79 degrees is hot but to get to the next level, 80 – although it’s just 1 more degree – requires a lot more heat.

And to challenge No. 1 — 1955 at 81.5 degrees — would that take the biggest flame thrower in 70 years, more than anything from the recent sweltering runs in 2010, 2011, 2012, 2020 and 2022?

No, because the highs aren’t the key.

July 2011’s average of the highs of 92.1 degrees at Reading Regional bested 1955’s 91.4, which was recorded in downtown Reading.

The key to July 1955 was the balmy overnights.

What might a month that beats 1955 look like? Probably a lot like July 2022 at Philadelphia International Airport.

There were 19 days of at least 90 degrees, which isn’t a record there or would be in Berks, but an average of the daily lows was a stuffy 73.7 degrees. That was 5 degrees higher than the average of the lows at Reading Regional.

The average temperature amid the concrete and asphalt last month at Philly International was 82.1 degrees.

That matter of normal, again

Only three of the 31 days last month were below normal in terms of average temperature and those departures were 1 or 2 degrees. Only one day had a double-digit departure to the high side.

But, what’s normal?

The weather service says normal is the average of most recent complete three decades, in this case 1991 through 2020.

The current normal for July of 76.1 degrees is the highest normal on record, propelled by the Julys in 2010, 2011, 2012 and 2020.

Most recently, July 2020’s 80.3-degree average was 5.4 above the normal of 74.9.

An increase of 1.2 degrees for normal is a big deal. It came about because the overall chilly 1980s dropped out of the calculation and last decade filled in.

Recent heat

The recent heat that culminated in a spike Thursday was part of a heat wave at the same hot spots in southeastern Pennsylvania: Philly International and Reading Regional.

There was no heat wave at Pottstown-Limerick Airfield between Pottstown and Limerick; Wings Field in Blue Bell, Montgomery County; or Brandywine Regional Airport near West Chester.

Even Lehigh Valley International Airport didn’t get to 90 degrees three days in a row.

However, if there’s a 90 on Saturday, Lehigh Valley and Wings will have registered a heat wave.

In another matter, the run of days with at least 80 degrees continues at Reading Regional. It is up to 43 through Friday, and it will likely stretch to 44 through Saturday. The record is 61 days from July 3 through Sept. 1 in 2016.

July 2016 was obviously also a near-miss month for every day reaching 80 degrees. It had 17 90-degree days and is No. 13 by average, pushed down two slots by later Julys in 2020 and 2022.

July weather in Berks

79 degrees: Average temperature

76.1 degrees: Normal

2.84 inches: Rainfall

4.77 inches: Normal

90-degree days: 12 (year: 20)

Records:

High temperature: 97 degrees on the 24th (96 in 1910, 1987, 2010 and 2016)

Warmest low: 77 degrees on the 21st (tie, 1940 and 2011)

Hottest Julys

81.5: 1955

80.4: 2011

80.3: 2020

79.5: 2012

79.2: 1949

79: 1952, 1999 and 2022

78.9: 1966

78.8: 1901, 2010

This list by average temperature, calculated by adding the daily highs and lows together and dividing by two.

Source: National Weather Service

July totals from the Berks Area Rainfall Networks

Mohnton, 6.87 inches; Lobachsville, 6.50; Shillington, 6.25; Wales Township building, 6.19; Adamstown, 6.04; Morgantown, 5.99; Reiffton, 5.97; Lincoln Park, 5.79; Knauers, 5.73; Cornwall Terrace, 5.62; Boyers Junction, 5.39; Wernersville, 5.11; Oley Furnace, 5.09; east Reading, 4.99; Wyomissing, 4.93; Henningsville, 4.59; Mohrsville southwest, 4.42; Boyertown and Gilbertsville, 4.40; Vinemont, 4.35; Gibraltar, 4.01; Cacoosing, 3.66; Birdsboro, 3.61; Greenfields, 3.35; Kutztown, 3.13; Womelsdorf, 2.92; Pine Grove, 2.88; Mohrsville, 2.83; Shartlesville, 2.77; Frystown, 2.65; Hamburg, 2.65; and Bernville, 2.59.

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