Iijima has a temperate climate with warm summers and freezing winters.
Temperatures peak in August and drop to their lowest in February, while rainfall is highest during autumn months.
Humidity remains high throughout the year, especially during winter months, creating cold and damp conditions.
| Month | 🌤️ | High | Low | Avg | Humid % | Rain (mm) | Wind (m/s) | Solar (kWh/m²) |
|---|---|---|---|---|---|---|---|---|
| January | ❄️ | 5.1°C | -15.2°C | -5.1°C | 87% | 50 | 2.5 | 2.47 |
| February | ❄️ | 7.5°C | -15.3°C | -3.9°C | 85% | 64 | 2.4 | 3.25 |
| March | ☔ | 12.5°C | -11.7°C | 0.4°C | 83% | 119 | 2.3 | 4.10 |
| April | ☔ | 18.0°C | -6.1°C | 5.9°C | 80% | 128 | 2.2 | 4.89 |
| May | ☔ | 21.3°C | -1.2°C | 10.1°C | 80% | 144 | 1.9 | 5.16 |
| June | 🌧️ | 23.8°C | 5.6°C | 14.7°C | 84% | 185 | 1.6 | 4.74 |
| July | 🌧️ | 26.4°C | 11.6°C | 19.0°C | 87% | 196 | 1.6 | 4.81 |
| August | 🌧️ | 26.9°C | 12.4°C | 19.7°C | 86% | 165 | 1.5 | 5.02 |
| September | 🌧️ | 24.9°C | 6.6°C | 15.7°C | 87% | 200 | 1.5 | 4.02 |
| October | ☔ | 20.3°C | -1.7°C | 9.3°C | 86% | 147 | 1.5 | 3.37 |
| November | 🌨️ | 14.9°C | -5.7°C | 4.6°C | 86% | 78 | 1.8 | 2.69 |
| December | ❄️ | 9.3°C | -12.0°C | -1.4°C | 86% | 48 | 2.3 | 2.23 |
Showing average climate conditions across 45 years (1981–2025)
🧥 Pack heavy layers and prepare for snow — this is a Severe Winter destination.
🌤️ Conditions are ideal for outdoor activities throughout the day in this Mild Summer.
☔ Heavy Rainfall expected — carry rain gear and plan outdoor activities around these months.
Monthly averages · 1981–2025 climate normals · °C
Temperatures rise steadily from spring, peak in August, and gradually decline through autumn into winter.
These seasonal patterns make summer ideal for outdoor activities, while winters bring freezing conditions and heavy snowfall.
Monthly rainfall · 1981–2025 seasonal trends · mm/month
Monthly averages · 1981–2025
💧 Humidity peaks at 87% in January · annual avg 85%
The warmest year in Iijima's recorded history was 2024 (avg: 9.4°C), while the coldest was 1986 (avg: 6.4°C).
Average annual high/low · Last 10 years · °C
Total annual precipitation · Last 10 years · mm/year
| Year | Min Temp | Avg Temp | Max Temp | Rainfall (mm) | Avg Humidity | Avg Wind |
|---|---|---|---|---|---|---|
2025 | -1.7°C | 8.5°C | 18.7°C | 1465 | 86% | 1.9 m/s |
2024 🌧️ | -0.3°C | 9.4°C | 19.0°C | 2284 | 87% | 1.9 m/s |
2023 🔥 | -1.4°C | 8.8°C | 19.1°C | 1731 | 84% | 1.9 m/s |
2022 | -1.8°C | 8.2°C | 18.2°C | 1747 | 86% | 1.8 m/s |
2021 | -1.6°C | 8.1°C | 17.9°C | 1878 | 86% | 2.0 m/s |
2020 | -1.2°C | 8.6°C | 18.3°C | 1873 | 85% | 2.0 m/s |
2019 | -1.0°C | 8.7°C | 18.4°C | 1622 | 85% | 1.9 m/s |
2018 | -2.2°C | 8.2°C | 18.6°C | 1712 | 85% | 2.0 m/s |
2017 | -2.4°C | 7.2°C | 16.7°C | 1466 | 84% | 1.9 m/s |
2016 | -2.1°C | 8.1°C | 18.4°C | 1678 | 85% | 1.8 m/s |
Showing 1 to 10 of 45 years
Based on 45 years of data (1981–2025), August is typically the hottest month in Iijima, Nagano, with average high temperatures around 26.9°C.
February is the coldest month in Iijima, with average low temperatures around -15.3°C.
September receives the most rainfall with approximately 200 mm, while December is the driest with 48 mm.
The highest recorded temperature was 29.7°C in August 1994. This is part of the historical record spanning 1981–2025.
The lowest recorded temperature was -20.7°C in February 1984.
This page covers 45 years of climate data from 1981 to 2025. As new data is added to the database the page automatically reflects the updated coverage.
Iijima receives the most sunlight in May with an average solar radiation of 5.16 kWh/m²/day. This solar radiation data, sourced from NASA POWER, is useful for solar energy planning and agriculture in Nagano.
All climate data is sourced from NASA POWER (Prediction Of Worldwide Energy Resources), based on MERRA-2 satellite and model data. It provides monthly averages for temperature, precipitation, humidity, wind speed, and solar radiation.
All weather data is sourced from NASA POWER (Prediction of Worldwide Energy Resources), a NASA project providing solar and meteorological data for renewable energy, building efficiency, and agricultural research.
