The National Weather Service issued a tornado watch for much of Southeast Pennsylvania, New Jersey and Delaware on Monday until 7 p.m. While having a tornado alert is not rare for the area, having one at this time of year is abnormal.
“This is unusually early,” said meteorologist Ray Martin, who works at NWS’s Mount Holly office. “Not the earliest we’ve ever seen, but usually it’s later in the season when we start to get a widespread threat like this.”
Tornado season in the area is typically late spring to mid-summer.
A wind advisory is also in effect until 2 a.m. Tuesday. The severe weather caused some local school districts, including Downingtown and Spring-Ford, to call for an early dismissal, while Philadelphia canceled outdoor afterschool activities. People around the area are recommended to stay inside.
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Watches are issued when conditions are favorable for the formation of tornadoes. Humid, moist air combined with a strong front from the west has the potential to create significant wind speeds up to 80 mph. Atmospheric instability could cause the wind direction to change and rotate, causing tornadoes.
Severe thunderstorms are likely to begin around 2 p.m., the NWS said. Localized flash flooding is possible near Philadelphia, and there could be minor coastal flooding in Ocean County.
“It’s a pretty significant threat,” Martin said. “Already today, we’ve seen quite a few strong thunderstorms. Over the afternoon into the evening, we’ll see that threat spread into our area.”
A tornado warning, which signals imminent threat of severe weather, has not been issued for the area yet, Martin said. But if storms strengthen, a warning is more likely.
Here is a reminder on the difference between a watch and a warning. Watch means conditions are favorable, while a warning means the hazardous weather is imminent. pic.twitter.com/F4i9NSf6vz
— NWS Mount Holly (@NWS_MountHolly) March 16, 2026
If a tornado warning is implemented, Martin recommended that people find shelter, preferably in a basement or a room away from windows.
After a particularly cold winter brought several feet of snow to Philadelphia, last week’s warmer temperatures, which reached the low 80s, were some brief respite before another cold front swept into the region. What’s to blame for the weather whiplash this month, according to Martin, is the stubborn nature of this winter’s freezing conditions.
“We had a very stagnant cold pattern through much of the winter and now it’s breaking down,” he said. “We’re trying to revert back to something more spring-like, and that’s a pattern that is not going to go too willingly.”