May 2024 was a generally a mild month for most of the Northeast. Like most months, it featured a mix of active and drier stretches, though an uptick in severe weather and flooding was prominent as it became more climatologically favored. Precipitation anomalies were a bit variable from the Mid Atlantic to New England, though most anomalies ran near average to ~1" above the normal monthly precipitation.
The first week of May started out rather warm for many across New Jersey / Pennsylvania and the Mid Atlantic with daily record highs eclipsing 90 degrees across climate sites on the 2nd and 8th! Additionally, while the first few days of the month were generally quiet, a system brought some showers to all across the Northeast during the span of the 4th - 5th with some showers / storms also moving across the Mid Atlantic over the following days. Localized heavy rainfall in excess of 1 - 1.5"+ accompanied the storms on the 6th.
The afternoon of the 8th then saw a bout of strong storms across New England leading to scattered reports of quarter sized hail, though the largest hailstones from this event measured upwards of 2"! Temperatures also trended cooler for many into the second week, especially towards the coast where highs ran as much as 6 - 12+ degrees below average in spots owing to a persistent onshore flow regime. This included daily record lows being set across many Northeast climate sites during the stretch of the 11th - 13th, where low temperatures in the upper 30s into the 40s were common. Also noteworthy during the second week of May included the strongest geomagnetic storm seen since 2003 during the night of the 10th. While there were plenty of clouds to contend with across the Northeast, those that were lucky enough were able to catch a glimpse of the rare aurora borealis! Furthermore, the second week of the month was pretty active and wet across much of the Northeast with many bouts of rain. This was the heaviest down into Southern Virginia where heavy rain during the 14th produced cumulative rainfall amounts of 1.5 - 3" leading to some localized flooding issues.
We are getting reports from across our area of the aurora borealis (aka the Northern Lights) being visible! What are you seeing tonight? Clouds may hinder your ability to see the full aurora in some areas! #NYwx #CTwx #NJwx https://t.co/GJA7lHUyrv
— NWS New York NY (@NWSNewYorkNY) May 11, 2024
Tweet from NWS New York discussing the geomagnetic storm and aurora borealis sightings across the area on May 10th, 2024.
This axis of heavy rain translated northeastward into Southern New England during the evening of the 15th into the morning of the 16th with as much as 3 - 5"+ falling across Southern CT and RI causing some poor drainage, roadway, and stream/creek flooding problems. Temperatures saw some variability during the second half of the month but commonly ran above average across many climate sites, typically on the order of 5 - 15 degrees. Otherwise, the 3rd and 4th weeks of the month featured a mix of drier stretches and showers/storms, some of which produced localized heavy rainfall and flooding. Most notable during this stretch was a potent disturbance that traversed the Northeast on the 23rd with strong storms leading to some scattered wind damage consisting of downed trees and powerlines stretching from Eastern PA and Northern NJ into the Hudson Valley. Some localized heavy rain and large hail reports up to ping pong ball sized also accompanied this activity. Additionally, after a weakening line of storms brought some wind damage to the Mid Atlantic during the night of the 26th, the next bout of severe weather occurred during the afternoon and evening of the 27th out ahead of an approaching cold front from Pennsylvania down into the Mid Atlantic. Spotty wind damage and isolated large hail was again notable, as well as 2 EF-1 rated tornadoes that touched down in Northern Pennsylvania.
Flooding along Elmgrove Ave on the East Side of Providence - Remember you should NEVER drive through a flooded roadway #RIwx https://t.co/IUDIaHvubP
— NWS Boston (@NWSBoston) May 23, 2024
Retweeted video by NWS Boston showing roadway flooding across Providence RI from heavy rainfall on May 23rd, 2024.
Overall, highs and lows generally ran 2 - 4 degrees above normal across much of the Northeast during the month. Precipitation wise, most areas ran near normal to ~1" above their normal monthly precipitation. Exceptions to this included across portions of Southern New England and Southern Virginia that actually finished 2 - 3"+ above normal. Meanwhile, portions of Southeastern PA into Southern NJ finished the month in a deficit on the order of 0.5 - 1.5" below normal.
