About 0.2°F per decade, measured from Hilo'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? Hilo's climate has warmed more slowly than most other cities in United States.
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
about the same
1970s
0 / yr
→
Recent
0 / yr
Winters about as cold as before
Average temperature
+0.8°F
1970s
74.0°F
→
Recent
74.8°F
A steady upward drift
Hot days above 90°F
1 more day
1970s
1 / yr
→
Recent
2 / yr
More days of serious heat
Rainy days
about the same
1970s
272 / yr
→
Recent
272 / yr
Rainfall pattern about the same
Hilo'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.
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.
February has cooled the most — about 0.4°F. The warming runs across the whole year, not just one season.
Methodology & sources
Temperature — the official 1991–2020 climate normals from NOAA's U.S. Climate Normals, measured at Hilo Intl AP 87 (NOAA GHCN station USW00021504), about 5 km from the city centre.