Despite an impressively active (and still ongoing) hurricane season, the Northeast was spared any direct tropical impacts for September. In fact, the month was rather quiet overall, and temperatures began taking a step down as the equinox passed. The lack of activity, particularly in the precipitation department, exacerbated an ongoing drought in New England, pushing it into parts of New York by the end of the month.
Tropical Storm Omar pushes well out to sea to start September 2020, Courtesy NOAA.
Tropical Storm Omar formed off of the East Coast on day one, but safely floated offshore away from the region. Just two days later on the 3rd, a tiny disturbance impacted Maryland and Delaware that resulted in numerous wind reports from a line of thunderstorms. One tornado managed to touchdown near Londontowne, MD that damaged a few homes and mowed down utility poles.
Despite that brief bout with severe weather, no more widespread outbreaks occurred. By the second week, a coastal low sent several waves of rain into the Mid-Atlantic, resulting in around an inch or more of rainfall for New York City and points south. Some amounts were a bit higher though, as Washington, D.C. picked up close to 3.00 inches. Following that disturbance, a series of high pressure systems left the Northeast with an unusually quiet stretch. Indeed, for most it was a two week period of unseasonably cool weather as departures fell up to 10 degrees below normal (periodically aided by high altitude smoke from western wildfires). High temperatures didn’t reach far into the 70s with many 60s observed, and nighttime lows became so cold at times that frost formed! The 20th-22nd was the coldest period in which the thermometer slipped into the 30s, including parts of Long Island, Connecticut, and interior New York and Pennsylvania. Allentown, PA broke a record each of these nights with temperatures ranging between 33 and 36 degrees. The only area that saw real rain during this stretch was Virginia on the 18th thanks to the remnants of Hurricane Sally.
A frosty start on September 21st, 2020 from Nazareth, PA. Photo courtesy of meteorologist Mike Mihalik.
On the 23rd, a particularly breezy day led to several dozen wildfires (mainly in Massachusetts) along with a few in Connecticut due to lack of rainfall, all of which was abnormal for this time of year. Beyond that, a bit of a regime change did shake the pattern for the last week, sending temperatures back above average. This led to a surge of moisture and rainfall on the 29th and 30th. While around an inch of rain fell along the I-95 corridor, it was nowhere near enough to break the drought in New England. It did help prevent cities like Hartford, CT and New York, NY from slipping well below their normals for the month, but didn’t quite save places like Boston, MA which saw less than an inch overall.
While September felt cool, most were close to normal with up to 1 degree departures in the warmer direction (only Washington, D.C. saw seasonably cooler temperatures). And while the month was not extremely dry per se, the three month precipitation departures since July were 5 to 10 inches below normal for eastern Connecticut on north into southern Maine. According to the US Drought Monitor, these areas as of September 29th are now in severe or extreme drought status. Hopefully another pattern change in October can lend some needed rainfall to the area.