Lehigh Valley weather: Summer 2020 ends with coldest September morning in 20 years

Autumn frost

Monday morning's low of 33 degrees in Allentown was officially the Lehigh Valley's coldest September temperature in 20 years. September lows have fallen below freezing only three times here, according to National Weather Service records dating back nearly 100 years.Sue Beyer | lehighvalleylive.com file photo

Tuesday is the first day of fall, but Monday morning felt like autumn was already well established.

The morning low of 33 degrees measured in Allentown was the coldest September temperature recorded in the Lehigh Valley in 20 years, according to National Weather Service data.

The area last saw September reach the freezing point Sept. 29, 2000. Another low of 33 degrees was recorded one day later. In 98 years of Lehigh Valley weather records, September lows have fallen below 32 degrees only three times – once in 1963 (31 degrees) and two consecutive dates in 1947 (31 and 30 degrees).

On average, our area will usually see its first sub-freezing low around mid-October, weather service data says.

Monday morning’s low set a new Lehigh Valley record for that date. Previously, the coldest Sept. 21 was 34 degrees in 1956. Sunday morning’s low of 36 was also a daily record.

As chilly as the week has started, the Lehigh Valley weather forecast calls for more seasonable temperatures by the weekend with highs expected to climb into the upper 70s and lows settling in the mid-50s over the next several days. There is no rain in the forecast.

As for the rest of the 2020 fall, projections by the National Weather Service’s Climate Prediction Center show above-normal temperatures possible across the entire continental U.S. over the next three months.

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Steve Novak may be reached at snovak@lehighvalleylive.com.

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