Niigata has warmed about 2.2°F between 1971 and 2020.
About 0.5°F per decade, measured from Niigata'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? Niigata'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
35 fewer nights
1970s
61 / yr
→
Recent
26 / yr
Milder winters — fewer frosts
Average temperature
+1.7°F
1970s
55.9°F
→
Recent
57.6°F
A steady upward drift
Hot days above 90°F
1 more day
1970s
16 / yr
→
Recent
17 / yr
More days of serious heat
Rainy days
8 fewer days
1970s
193 / yr
→
Recent
185 / yr
Drier on average
Niigata'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 20 fewer freezing nights a year compared with the 1970s.
Methodology & sources
Temperature — the official 1991–2020 climate normals from the Japan Meteorological Agency, measured at Niigata, about 4 km from the city centre.