Our winters are warming, despite this year's cold spell

Seattle's winter was colder than usual this year — but our winters are still trending warmer over time.

Why it matters: Warm winters can exacerbate drought (because there's less snowmelt in the spring), wreak havoc on crops and gardens, and spell disaster for towns built around skiing, snowboarding and similar pursuits.

By the numbers: In Seattle, our average temperature from December through February is now about 42°F — nearly a degree higher than what it was in 1970.

• That's according to a new analysis of National Oceanic and Atmospheric Administration numbers from Climate Central, a nonpartisan research and communications group.

Zoom in: Seattle's average temperature this winter was a little lower than the trendline, averaging 41°F from December to February, according to Climate Central. That was predicted last year when it became clear we would have our third La Nina winter in a row.

• Still, temperatures in Seattle have been trending upward by about 0.2°F a decade over the past half-century, according to NOAA's National Centers for Environmental Information.

The big picture: Winter is the fastest-warming season for much of the continental U.S.

• About 80% of the country now has at least seven more winter days with above-normal temperatures compared to 1970, per Climate Central.
• Seasonal snowfall is declining in many cities — though heavy snowstorms can still happen when temperatures are cold enough.

• In fact, precipitation extremes are happening more frequently and getting more intense, which can lead to feast or famine snowfall.

Driving the news: Not only are winters warming overall, but cold snaps are becoming less severe and shorter in duration, the latest research shows.

• That's partly because the Arctic is warming at three to four times the rate of the rest of the world.
• In other words, our global refrigerator is warming up, making it harder to get record-breaking cold for days on end when weather patterns transport Arctic air southward.

The bottom line: Over the coming years, most of us can expect to feel climate change's effects acutely during the winter months.