About 0.8°F per decade, measured from Oulu'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? Oulu's warming is broadly in line with other cities in Finland — 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
99 fewer nights
1970s
195 / yr
→
Recent
96 / yr
Milder winters — fewer frosts
Average temperature
+3.5°F
1970s
35.5°F
→
Recent
39.0°F
A steady upward drift
Hot days above 90°F
about the same
1970s
0 / yr
→
Recent
0 / yr
About the same number of heat days
Rainy days
154 fewer days
1970s
154 / yr
→
Recent
0 / yr
Drier on average
Oulu'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 58 fewer freezing nights a year compared with the 1970s.
When in the year the change shows up
How much warmer each month is now than in the 1970s.
Useful if you garden or care about a particular season —
otherwise the headline above already has the answer.
January has warmed the most — about 3.5°F. The warming runs across the whole year, not just one season.
Methodology & sources
Temperature — 1991–2020 normals computed from 22 years of daily observations at Oulunsalo Oulun Lentoasema, a weather station, about 11 km from the city centre. The underlying daily records come from NOAA's global station network.