Maine Faces a Warmer, Wetter Winter as Strong El Niño Shifts Weather Patterns
A strong El Niño warming the central and eastern Equatorial Pacific Ocean is setting up a winter for Maine and New Hampshire that will look sharply different from last year, wgme.com reported. The seasonal outlook calls for warmer-than-normal temperatures, above-normal precipitation, and below-normal snowfall across the two states.
Southern and central Maine can expect roughly 75 percent of their typical snowfall, according to the forecast. While Portland averages 68.7 inches of snow annually, this upcoming season is projected to bring closer to 45 to 55 inches.
How the Pacific Warming Alters the Jet Stream
The primary driver behind the shift is a powerful El Niño pattern in the Pacific Ocean. The warming sea surface temperatures alter the jet stream across North America, typically weakening the northern polar jet stream and pushing it further north while strengthening the southern subtropical jet stream.
This configuration routinely delivers a warm winter pattern to the northern half of the United States while leaving the southern half cool and wet. For Maine and New Hampshire, that means fewer accumulating snow events and a higher frequency of rain and mixed precipitation.
While northern New England braces for a lighter snow season, the El Niño playbook often writes a different story just to the south. Four of the top five snowstorms in Washington, D.C., have occurred during strong or very strong El Niño winters, including the February 2010 storm known as “Snowmageddon.” Similarly, three of the top five snowstorms in New York City hit during El Niño winters, including the January 2016 storm “Jonas” that dropped over two feet of snow in Central Park.
A History of Stormy, Non-Snow Winters
Below-normal snowfall in Maine does not mean a quiet weather season. Past strong El Niño winters have brought impactful, damaging storms that bypassed snow entirely, including:
- An ice storm from January 5th through 9th, 1998.
- A high-wind and flooding event on February 25th, 2010, which brought wind gusts reaching 78 miles per hour in Portland—the strongest on record.
- Rare winter thunderstorm wind damage on February 25th, 2016.
- Inland flooding caused by six inches of rain and snowmelt on December 18th and 19th, 2023.
- Record coastal flooding on January 13th, 2024.
- An ice storm on March 23rd and 24th, 2024.
Historical data from previous strong and very strong El Niño winters—including 1982–83, 1991–92, 1997–98, 2015–16, and 2023–24—shows that for Portland from December through February, 80 percent of those winters were warmer than normal, 80 percent saw above-normal precipitation, and 100 percent recorded below-normal snowfall. Seasonal computer modeling for the upcoming winter maintains that strong signal for warmth and increased precipitation across Maine and New Hampshire.
The Wildcard: Early Stratospheric Warming
A rare and unexpected Sudden Stratospheric Warming event near the North Pole introduces uncertainty into the forecast. As the strongest such event this early in the season since 1968, it could weaken the polar vortex, allowing modified Arctic air to drift south and disrupt the expected El Niño pattern.
If that disruption takes hold, New England could see an early start to winter in mid-to-late November and early December. Strong El Niño seasons also tend to feature a quick transition to spring by March, potentially bringing an early start to the maple sugaring season and helping to end a recent drought in 2027.
