It does not actually rain every weekend, but many parts of the southern and eastern United States have seen outdoor plans disrupted this spring by a spate of weekend storms. The Memorial Day weekend was the wettest in Burlington, Vermont, in over a century, while flooding in Beeville, Texas, required water rescues.
Meteorologists say there is no scientific reason why weekends should attract more rain. The timing is coincidental, although the hot, humid season naturally brings an increased chance of thunderstorms. As Steve Decker, an associate professor at Rutgers University, put it: "I believe the issue with rain on holiday weekends is simply luck of the draw."
The specific storms over the Memorial Day weekend were driven by an upper-level area of high pressure that produced abundant moisture, with the polar jet stream pushing storm systems from the northeastern Pacific through the Ohio Valley. AccuWeather senior meteorologist Paul Pastelok noted that areas like the Northeast were in a "sweet spot," but added: "Timing wise, I can't explain that. It just seems like we got into a funk that everything wanted to come on weekends and spoil things."
While some social media users have blamed air pollution, climate change or cloud seeding, experts say these factors do not influence when storms form. However, climate change can make rain events heavier when they do happen. "Climate change is certainly increasing the upper limit on moisture in storms but that influence is most clear in intense storms and in increasing variability," said Matthew Barlow, a professor of climate science at the University of Massachusetts Lowell.
Air pollution can affect precipitation behaviour, but any "weekend effect" would be minor, according to Texas State Climatologist John Nielsen-Gammon. The impending El Niño pattern is also not connected to the recent rainy weekends, said James Booth of The City College of New York. Additionally, changes to the jet stream can slow storms down, causing them to dump more rain in one place, noted Tom Rickenbach of East Carolina University.
Ultimately, experts agree that the apparent concentration of rain on weekends is a matter of chance. Yet with a warmer atmosphere able to hold more moisture, the potential for intense downpours remains a concern regardless of the day.
