Gunma Prefecture is Japan's hot spring capital, mountain playground, and silk heritage land — a landlocked prefecture north of Tokyo where volcanic peaks, therapeutic onsen, pristine highland forests, and the UNESCO World Heritage Tomioka Silk Mill define a destination unlike anywhere else in Japan.
Gunma Prefecture has a continental-influenced climate accentuated by its mountain topography. The lowland areas around Maebashi and Takasaki are among Japan's hottest in summer (regularly exceeding 37°C / 99°F) but the mountain regions are 5–10°C cooler. Winters are cold with heavy snowfall in the mountains. Kusatsu Onsen (1,200m elevation) maintains a year-round average temperature about 7°C cooler than Tokyo. The prefecture lies in the rain shadow of the mountains, receiving less rainfall than coastal Kanto, but summer thunderstorms in the mountains can be intense.
Best time to visit
Best: Year-round
Avoid: None
Month-by-month weather
Typical conditions throughout the year.
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The seasons
What to expect in each part of the year.
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Crowds & peak times
When to expect tourists and when to avoid them.
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- Period
- Golden Week (late April–early May)
- Level
- Extremely busy
- Note
- All onsen towns, national parks, and mountain roads overwhelmed. Book accommodation 3+ months ahead. Expect 2–3x normal prices.
- Period
- Obon (mid-August)
- Level
- Extremely busy
- Note
- Japanese domestic travel peak. Avoid unless you have confirmed bookings made months ahead.
- Period
- October weekends
- Level
- Very busy
- Note
- Autumn foliage draws massive crowds to Agatsuma Gorge and Oze. Weekday visits are significantly more peaceful.
- Period
- December–February (excluding ski resorts)
- Level
- Very quiet
- Note
- Onsen towns at their most atmospheric with fewer visitors. Great value.
- Period
- June (rainy season)
- Level
- Quiet
- Note
- Fewest crowds of any season. Onsen discounts common. Oze wetlands are at their most vibrant.
Major events & festivals
Time your visit around what matters.