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Isesaki, Gunma Weather by Month and Climate Averages
Monthly normals · Rain · Snow
Sunshine · Freeze dates · Records · Best time to visit
What is the weather like in Isesaki, Gunma?
Isesaki, Gunma gets 1169 mm of precipitation a year over about 99 rainy days. August is the warmest month (average high 32°C) and January the coldest (average low -1°C).
Humid subtropical climate
Isesaki, Gunma has hot summers and chilly winters. Daytime highs range from about 9°C in January to 32°C in August. September is usually the wettest month. The most comfortable time to visit is typically April to May and October, when daytime highs sit near 22°C.
| Season | Months | Avg low | Avg high |
|---|---|---|---|
| Winter | Dec–Feb | 0° | 11° |
| Spring | Mar–May | 8° | 19° |
| Summer | Jun–Aug | 21° | 30° |
| Autumn | Sep–Nov | 13° | 22° |
How much rain does Isesaki get?
Isesaki gets 1169 mm of precipitation in an average year, spread over about 99 days with measurable rain. That is fewer rainy days than 77% of Japan.
September is the wettest month, with 193 mm. December is the driest, with 22 mm. July has the most rainy days, about 15.
The longest dry spell in the last five years lasted 41 days, to February 6, 2026.
From October 2025 to September 2026 Isesaki got 2460 mm of rain, against a normal of 1169 mm for those months. September 2026 had the most, with 1427 mm.
Isesaki weather by month
Isesaki weather in January
In January, Isesaki averages a high of 9°C and a low of -1°C. It gets 26 mm of precipitation over about 3 rainy days. Estimated sunshine is 60% of daylight hours, derived from ERA5 cloud cover. The January record high is 19°C (1996) and the record low is -8°C (1970).
Isesaki weather in February
In February, Isesaki averages a high of 10°C and a low of -1°C. It gets 24 mm of precipitation over about 4 rainy days. Estimated sunshine is 57% of daylight hours, derived from ERA5 cloud cover. The February record high is 23°C (1987) and the record low is -9°C (1981).
Isesaki weather in March
In March, Isesaki averages a high of 14°C and a low of 3°C. It gets 53 mm of precipitation over about 7 rainy days. Estimated sunshine is 46% of daylight hours, derived from ERA5 cloud cover. The March record high is 27°C (1998) and the record low is -7°C (1977).
Isesaki weather in April
In April, Isesaki averages a high of 19°C and a low of 8°C. It gets 71 mm of precipitation over about 8 rainy days. Estimated sunshine is 43% of daylight hours, derived from ERA5 cloud cover. The April record high is 32°C (1983) and the record low is -2°C (1978). April is one of the most comfortable months to visit.
Isesaki weather in May
In May, Isesaki averages a high of 24°C and a low of 13°C. It gets 94 mm of precipitation over about 9 rainy days. Estimated sunshine is 33% of daylight hours, derived from ERA5 cloud cover. The May record high is 37°C (1993) and the record low is 3°C (1991). May is one of the most comfortable months to visit.
Isesaki weather in June
In June, Isesaki averages a high of 27°C and a low of 18°C. It gets 144 mm of precipitation over about 13 rainy days. Estimated sunshine is 24% of daylight hours, derived from ERA5 cloud cover. The June record high is 39°C (2022) and the record low is 8°C (1978).
Isesaki weather in July
In July, Isesaki averages a high of 31°C and a low of 22°C. It gets 179 mm of precipitation over about 15 rainy days. Estimated sunshine is 24% of daylight hours, derived from ERA5 cloud cover. The July record high is 40°C (2001) and the record low is 12°C (1976).
Isesaki weather in August
In August, Isesaki averages a high of 32°C and a low of 23°C. It gets 186 mm of precipitation over about 12 rainy days. Estimated sunshine is 32% of daylight hours, derived from ERA5 cloud cover. The August record high is 41°C (2025) and the record low is 15°C (1976).
Isesaki weather in September
In September, Isesaki averages a high of 27°C and a low of 19°C. It gets 193 mm of precipitation over about 12 rainy days. Estimated sunshine is 26% of daylight hours, derived from ERA5 cloud cover. The September record high is 38°C (1984) and the record low is 8°C (1995).
Isesaki weather in October
In October, Isesaki averages a high of 22°C and a low of 13°C. It gets 137 mm of precipitation over about 8 rainy days. Estimated sunshine is 42% of daylight hours, derived from ERA5 cloud cover. The October record high is 32°C (2026) and the record low is 3°C (1971). October is one of the most comfortable months to visit.
Isesaki weather in November
In November, Isesaki averages a high of 17°C and a low of 7°C. It gets 40 mm of precipitation over about 5 rainy days. Estimated sunshine is 61% of daylight hours, derived from ERA5 cloud cover. The November record high is 26°C (2019) and the record low is -2°C (1974).
Isesaki weather in December
In December, Isesaki averages a high of 12°C and a low of 2°C. It gets 22 mm of precipitation over about 3 rainy days. Estimated sunshine is 65% of daylight hours, derived from ERA5 cloud cover. The December record high is 25°C (1990) and the record low is -6°C (1976).
Sunshine, humidity and wind in Isesaki
December is the sunniest month in Isesaki, with estimated sunshine of 65% of daylight hours from ERA5 cloud cover. June is the cloudiest, at 24%. The annual cloud-cover estimate is 43% of daylight hours; it is not a measurement of sunshine duration. Isesaki is sunnier than 90% of Japan.
Humidity peaks in September at 79% and is lowest in February at 55%.
Isesaki has about 29 days a year above 32°C. Isesaki is hotter than 76% of Japan.
First and last freeze in Isesaki
The first fall freeze in Isesaki typically comes around December 9, and the last spring freeze around March 23. That leaves a frost-free growing season of about 261 days.
Isesaki weather records
These records cover MAEBASHI during 1970–2026. Earlier records or other stations in the city may differ.
The hottest temperature on record at the Isesaki station is 41°C, on August 5, 2025. The coldest is -9°C, on February 27, 1981.
The wettest day in the available station history brought 340 mm of precipitation, on August 23, 1993.
45 all-time records have been set at the station since 1970.
The best time to visit Isesaki
The most comfortable time to visit is typically April to May and October, when daytime highs sit near 22°C.
Winter (December–February) is chilly, with average highs around 10°C and lows near 0°C.
Spring (March–May) is mild, with average highs around 19°C and lows near 8°C.
Summer (June–August) is hot, with average highs around 30°C and lows near 21°C. It can feel humid.
Autumn (September–November) is warm, with average highs around 22°C and lows near 13°C.
Monthly climate
| Month | Average low | Average high | Precip | Rain days | Humidity | Estimated sunshine | Record high | Record low |
|---|---|---|---|---|---|---|---|---|
| January | -1° | 9° | 26 mm | 3 | 58% | 60% | 19° | -8° |
| February | -1° | 10° | 24 mm | 4 | 55% | 57% | 23° | -9° |
| March | 3° | 14° | 53 mm | 7 | 59% | 46% | 27° | -7° |
| April | 8° | 19° | 71 mm | 8 | 61% | 43% | 32° | -2° |
| May | 13° | 24° | 94 mm | 9 | 67% | 33% | 37° | 3° |
| June | 18° | 27° | 144 mm | 13 | 74% | 24% | 39° | 8° |
| July | 22° | 31° | 179 mm | 15 | 77% | 24% | 40° | 12° |
| August | 23° | 32° | 186 mm | 12 | 77% | 32% | 41° | 15° |
| September | 19° | 27° | 193 mm | 12 | 79% | 26% | 38° | 8° |
| October | 13° | 22° | 137 mm | 8 | 72% | 42% | 32° | 3° |
| November | 7° | 17° | 40 mm | 5 | 67% | 61% | 26° | -2° |
| December | 2° | 12° | 22 mm | 3 | 61% | 65% | 25° | -6° |
Station: MAEBASHI, 15 km from the city. Temperature normal baseline: 1991–2020, calculated from available NOAA GHCN-Daily observations. Available station history: 1970–2026; record values refer to this station and period, not the entire city’s history. Precipitation includes rain and the water equivalent of frozen precipitation; snowfall depth is shown separately when available. Sources and methods
From ERA5 reanalysis. Sunshine is estimated from cloud cover.
Isesaki climate questions
How much rain does Isesaki get?
Isesaki gets 1169 mm of precipitation in an average year, over about 99 rainy days.
What is the wettest month in Isesaki?
September is the wettest month in Isesaki, with 193 mm. December is the driest, with 22 mm.
How many rainy days does Isesaki have a year?
Isesaki has about 99 days with measurable rain in an average year. July has the most, about 15.
What is the hottest month in Isesaki?
August is the warmest month in Isesaki, with an average high of 32°C.
What is the coldest month in Isesaki?
January is the coldest month in Isesaki, with an average low of -1°C.
What is the record high temperature in Isesaki?
Within the available 1970–2026 station history, the record high at the Isesaki station is 41°C, set on August 5, 2025. The record low is -9°C, on February 27, 1981.
What is the sunniest month in Isesaki?
December is the sunniest month in Isesaki, with estimated sunshine of 65% of daylight hours from ERA5 cloud cover. June is the cloudiest.
When is the first frost in Isesaki?
The first fall freeze in Isesaki typically comes around December 9. The last spring freeze is around March 23.
What is the best time to visit Isesaki?
The most comfortable time to visit is typically April to May and October, when daytime highs sit near 22°C.