Seattle's winter weather outlook: Above-average rainfall expected according to meteorologists

After a summer of record-breaking heat and bone-dry conditions, Western Washington is receiving its first stint of cooler, fall-like weather this week with an incoming cold front. And residents should be prepared for more rain than usual this winter, according to meteorologists.

Experts from the National Weather Service (NWS) in Seattle detailed an outlook for the upcoming winter season during the annual stakeholders meeting on Tuesday, forecasting above-average rainfall in Western Washington region for the months of October, November and December.

While precipitation totals will likely increase compared to previous years for a drizzly start to the winter months, temperatures for the last three months of the year are expected to remain near average.

"The odds are that we will see above normal precipitation for this three month period," said NWS Warning Coordination Meteorologist Reid Wolcott. "When we look at temperatures, there's an equal chance of seeing above, below or near normal temperatures throughout the season."

Seasonal precipitation for the early months of 2022 — January, February and March — is also expected to be above-average according to NWS. However, the outlook also points to below-average temperatures for that three month period.

The wetter winter might be spurred on by a La Niña event: the National Oceanic and Atmospheric Administration is currently predicting a 70-80% chance that La Niña will continue through the 2021-2022 winter. In Western Washington, La Niña winters are marked by more rain and cooler temperatures than usual, with increased likelihood for events such as lowland snow.

La Niña events often occur in consecutive winters in what climate scientists call a "double dip." While last season's event was on the stronger side, the strength of this year's event and when it will begin is still uncertain. However, Wolcott noted that this La Niña did appear to be weaker than last year's event.

"This outlook, as a whole throughout the next six months, is pretty similar to what we were looking at last year," Wolcott said. "It is likely that we will see heavy rainfall and flooding, we will probably see some wind and we'll see some snow, maybe not in the lowlands but we really don't know at this point."

Earlier in the year, the National Oceanic and Atmospheric Administration (NOAA) charted a new climate outlook for the region, noting that it had become wetter and warmer compared to 30 years ago. While total amount of precipitation received each year has increased, the number of rainy days per year has stayed on trend with an average of 156 rainy days compared to a slightly lower 152 days in the last recorded period.