Valley tops charts for rain, heat
High overnight temperatures drive up Allentown’s averages
This summer, Allentown, like much of the rest of the country, has been abnormally hot. Temperatures ticked up in May, and then June. The lingering sun of late July proved positively blistering. And as sweltering August afternoons slipped into sweaty evenings, the thermometer continued to crest above average.
If your electric bill soared these past three months, take comfort in knowing you were not alone.
When the summer is said
and done, Allentown will rank among the top 35 major climate sites in the Northeast for high temperatures and precipitation at a time when extreme weather and widespread heat seem to be the new seasonal norms. Heat waves may not have been unprecedented this summer, but are happening now on a planet that is seeing hotter nights than before.
“There is something anomalous about all of this data for Allentown, and it’s the overnight temperatures. It’s all related to the overnight lows,” said meteorologist Ed Vallee of Empire Weather, noting how the increase in summer nighttime temperatures are an example of how small shifts in average temperature can lead to overall extremes.
According to the Northeast Regional Climate Center, 32 of the region’s 35 major climate sites experienced a warmer-than-normal August, with 10 ranking this August among their 20 warmest on record. At the top of the chart was Allentown, with an average August temperature of 75 degrees, or 3.3 degrees above average (and good for the city’s 11th-warmest August on record). At least 18 nights were above 64 degrees.
It fits with a nationwide trend highlighted last year by the National Oceanic and Atmospheric Administration, which showed that nationwide, summer nights have warmed at nearly twice the rate of days, with overnight low temperatures increasing 1.4 degrees per century since 1895, when national temperature records began.
No other climate site in the Northeast was close to Allentown last month in terms of exceeding its normal temperature. Baltimore’s departure-from-normal was 2.8 degrees. Harrisburg was 2.7 degrees. Scranton, Boston and Washington, D.C., all saw temperatures 2.0 degrees above normal.
August precipitation, hit or miss across some of the major climate sites, was certainly a “hit” in Allentown. The city had 4.79 inches of rain, 130% of normal. It was tied for the eighth-wettest climate site in the Northeast for the month, with the measurement tying Dulles Airport, Virginia.
For overall summer precipitation, Allentown was near the top again among all major climate sites. Twenty were wetter than normal, data show, with Allentown tops on the list at 20.10 inches, but second overall in percent above normal. Scranton had 18.87 inches, or 168% of normal, while Allentown was 155% above normal.
It will rank as the city’s fifthwettest summer overall, with multiple dates where record rainfall occurred. On July 12, 2.75 inches of rain fell at the airport and smashed the previous record of 1.17 inches set in 1950. A record rainfall of 2.50 inches followed on July 23, beating the old record of 1.54 inches for the date set in 1938.
“When you have more moisture in the atmosphere, just in terms of thermodynamics, it’s harder to cool the atmosphere down,” Vallee said, noting that a complicated range of factors affect these overall numbers including precipitation, dew points, prevailing winds, proximity to the ocean, and green spaces (or lack thereof ) in neighborhoods.
Impervious, heat-absorbing surfaces, for example, can elevate temperatures in cities well beyond the norm.
A blue heron looks for dinner in July after heavy rain brought flooding to Cedar Beach Park near the Rose Garden in Allentown. When the summer is said and done, Allentown will rank among the top 35 major climate sites in the Northeast for high temperatures and precipitation.