About 0.6°F per decade, measured from Rifu's official daily weather records, 1971–2020. Individual years still bounce around — some recent ones came in cool — but the long-term line has clearly risen.
Is that a lot? Rifu's warming is broadly in line with other cities in Japan — 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
47 fewer nights
1970s
91 / yr
→
Recent
44 / yr
Milder winters — fewer frosts
Average temperature
+2.2°F
1970s
53.4°F
→
Recent
55.6°F
A steady upward drift
Hot days above 90°F
4 more days
1970s
6 / yr
→
Recent
10 / yr
More days of serious heat
Rainy days
about the same
1970s
120 / yr
→
Recent
120 / yr
Rainfall pattern about the same
Rifu's temperature, year by year
Average temperature for each year from 1971 to 2020.
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 28 fewer freezing nights a year and about 2 more days above 90°F compared with the 1970s.
Methodology & sources
Temperature — the official 1991–2020 climate normals from the Japan Meteorological Agency, measured at Shiogama, about 3 km from the city centre.