National Weather Service meteorologists forecast that western Montana will experience a warmer and drier winter than average, with snowfall expected to reach 75% to 85% of normal.

The outlook comes as forecasters anticipate a strong-to-very strong El Niño from January through March 2027. NOAA’s Climate Prediction Center said the chances remain high for an event that would exceed previous El Niños recorded since 1950.

Winter outlook

Brian Conlan, a Missoula-based National Weather Service meteorologist, said the El Niño advisory has been posted and that the climate pattern is already underway. “We are already in an El Niño,” Conlan said.

Across the northern United States, meteorologists forecast warmer and drier conditions, while the southern United States is expected to see wetter weather. Historically, El Niño winters have brought warmer and drier conditions to western Montana.

Conlan cautioned that the seasonal pattern does not determine every stretch of winter. Some El Niño seasons have included numerous wet and cold days even when the overall seasonal average was warmer or drier. He said the term “very strong” describes a greater probability of widespread effects, rather than the intensity of every individual weather event.

Snowpack and valley conditions

Prolonged high pressure could produce warmer temperatures at higher elevations while trapping cold air in valleys. Those conditions can bring fog and freezing rain, and Conlan said strong valley inversions and early flooding could affect western Montana.

Climate records for Kalispell from 1991 through 2020 show fewer cold days and less snowfall during strong El Niño events. Kalispell averages 27 days per year below 10 degrees Fahrenheit and 10 days below zero in normal years. During strong El Niño events, those averages fall to 19 days below 10 degrees and 6.5 days below zero.

Average annual snowfall in Kalispell is 54 inches, compared with 39 inches during strong El Niño events.

Snow-water-equivalent records from Noisy Basin in the northern Swan Range also show that snowpack has not historically reached the 90th percentile during El Niño winters. The monitoring site sits at 6,070 feet.

The 2016 El Niño did not push snow-water equivalent above the 80th percentile. In 1987, levels in the Swan Range fell within the lowest 10% of all winters. Snow in the range can melt quickly in spring, producing rapid runoff.

“An average is just an average,” Conlan said.