About 0.5°F per decade, measured from Portland's official daily weather records, 1971–2025. Individual years still bounce around — some recent ones came in cool — but the long-term line has clearly risen.
Is that a lot? Portland's warming is broadly in line with other cities in United States — neither unusually fast nor unusually slow.
What has actually changed
Each card compares the 1970s (the first ten years of the
record) with recent years (the last ten) — the same span
the headline and the chart use.
Freezing nights
10 fewer nights
1970s
40 / yr
→
Recent
30 / yr
Milder winters — fewer frosts
Average temperature
+1.6°F
1970s
53.8°F
→
Recent
55.5°F
A steady upward drift
Hot days above 90°F
6 more days
1970s
13 / yr
→
Recent
19 / yr
More days of serious heat
Rainy days
3 more days
1970s
151 / yr
→
Recent
154 / yr
Wetter on average
Portland's temperature, year by year
Average temperature for each year from 1971 to 2025.
a warmer-than-average year a cooler-than-average year
Each bar is one year. Most recent years sit above the older ones.
Some recent years still came in cool — warming is a slope,
not a straight climb.
In day-to-day terms, that long-term shift shows up as about 5 fewer freezing nights a year compared with the 1970s.
Methodology & sources
Temperature — the official 1991–2020 climate normals from NOAA's U.S. Climate Normals, measured at Portland Intl AP (NOAA GHCN station USW00024229), about 10 km from the city centre.