Apr 2, 2024 - Climate

What warm, spring temperatures mean for Oregon

A photo showing swimmers in a river with evergreen trees in the background.

Warm and dry conditions in the spring of 2021 contributed to the deadly heat dome that summer. Photo: Nathan Howard/Getty Images

April in Portland is off to a warmer-than-usual start — with temperatures in the mid-to-high 60s — and the rest of the month could be drier than average too, some forecasters predict.

Why it matters: Warmer spring days bring relief to sun-starved Portlanders, but higher-than-average springtime temperatures can also cause earlier snowmelt and prolong wildfire seasons.

Driving the news: While the metro's temperatures early this week are above the average high of 53° this time of year, cooler days and rain will follow Wednesday and Thursday, Thomas Schuldt, a meteorologist with the National Weather Service in Portland, told Axios.

  • But for the rest of the month, the Portland area is likely to experience higher than normal temperatures and below-average precipitation, Schuldt said.

The big picture: Average spring temperatures in Portland have risen three degrees between 1970 and 2023, according to research and communications nonprofit Climate Central.

  • The group's analysis is based on NOAA data and looks at the meteorological spring, from March 1 to May 31.

Between the lines: Snowpack in Oregon typically peaks in April, and its size directly impacts water supply levels that help fight wildfires and fuel agricultural irrigation throughout the summer.

  • Snowpack in the state has declined 25-50% since 1970, according to Larry O'Neill, Oregon's state climatologist.

Threat level: "If the snowpack is small or if it melts out too early, we often see drought impacts due to irrigation water shortages," O'Neill told Axios.

  • "Low streamflows also lead to increased incidence of algal blooms and municipal water quality issues."
  • Warmer spring temperatures can also quickly dry out soil and vegetation and "set the stage for increased wildfire risk during the mid-to-late summer," he said.

Flashback: Portland is prone to wacky April weather. The warmest April day ever recorded was 90° on April 30, 1998.

  • Meanwhile, two inches of snow fell at PDX on April 11, 2022, the latest date the city has seen snow in at least 80 years.
  • But just five days prior, temperatures had already reached 75° — leading to a spring whiplash and anguishing gardeners who had just sowed seeds.
  • In 2021, Portland recorded its driest April on record, receiving only about 27% of normal precipitation.
  • O'Neill said studies have shown that the historically dry spring contributed to the deadly heat dome later that year.
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