Mount Akagi Volcano
Volcanic mountain and caldera in Gunma Prefecture
Mount Akagi is a volcanic massif in Gunma Prefecture with caldera lakes such as Onuma-local hikers use forest trails, and winter sports take advantage of nearby slopes.
Mount Akagi at a Glance#
Address: Mount Akagi, Gunma Prefecture, Japan
About Mount Akagi#
Mount Akagi is a volcanic mountain complex in Gunma Prefecture, Japan, characterized by a broad caldera and a series of peaks surrounding crater lakes such as Lake Ōnuma. The mountain is a prominent natural feature north of the Kantō plain and is used for hiking, winter sports on lower slopes and seasonal recreation.
The volcanic complex was active in the geological past and now presents as a set of forested ridges and lakes within a caldera; trails and roads provide access to lakeside viewpoints and alpine ridges. The area is a regionally important scenic and recreational destination.
Mount Akagi lies northwest of the cities of Maebashi and Takasaki in central Gunma Prefecture, forming part of the inner volcanic arc north of the Tokyo metropolitan area.
- Volcanic caldera and lake: A dormant volcanic complex with a caldera that contains Lake Ōnuma, widely used for day hikes and scenic drives from nearby cities.
What to See#
- Lake Ōnuma: Ōnuma (Lake Onuma) is a caldera lake on the mountain’s flank that is a popular scenic and recreational spot with trails and viewpoints.
- Volcanic summit complex: Several volcanic peaks and ridges form the complex summit area, with hiking routes linking summits and lakes within the caldera structure.
How to Get to Mount Akagi#
Mount Akagi is reached by bus or car from Takasaki and Maebashi; regional buses serve the lake areas and trailheads in season. Driving offers the greatest flexibility to reach higher trailheads.
Tips for Visiting Mount Akagi#
- Visit Lake Onuma in the lower slopes for peaceful views and shorter walks that are less crowded than summit routes.
- If attempting the ascent, check trailhead conditions and seasonal services in Gunma Prefecture.
- Combine with visits to Takasaki or Shibukawa for regional cultural sites.
Best Time to Visit Mount Akagi#
Late spring through autumn is best for walking and enjoying the lakes; winter requires winter equipment.
Weather & Climate near Mount Akagi#
Mount Akagi's climate is classified as Warm-Summer Continental - Warm-Summer Continental climate with mild summers (peaking in August) and freezing winters (coldest in February). Temperatures range from -8°C to 23°C. Abundant rainfall (1866 mm/year), wettest in August.
| Month | Comfort | Temp | Feels | Rain | Sky | Humidity | Wind | UV | Daylight |
|---|---|---|---|---|---|---|---|---|---|
| January | Poor | -8° - 1° | -9° | 54 mm | some cloud | 82% | 4.0 m/s | 0.3 low | 9.8h |
| February | Poor | -8° - 1° | -9° | 70 mm | partly cloudy | 80% | 4.2 m/s | 0.6 moderate | 10.7h |
| March | Acceptable | -6° - 4° | -6° | 93 mm | partly cloudy | 77% | 4.3 m/s | 0.8 moderate | 11.8h |
| April | Acceptable | 0° - 11° | 2° | 135 mm | partly cloudy | 75% | 4.6 m/s | 1.2 high | 13.0h |
| May | Acceptable | 5° - 16° | 10° | 152 mm | overcast | 76% | 4.1 m/s | 1.4 high | 14.0h |
| June | Acceptable | 10° - 18° | 14° | 224 mm | overcast | 80% | 3.4 m/s | 1.4 high | 14.5h |
| July | Good | 14° - 22° | 18° | 236 mm | overcast | 82% | 3.4 m/s | 1.6 very high | 14.2h |
| August | Good | 15° - 23° | 19° | 322 mm | overcast | 82% | 3.6 m/s | 1.6 very high | 13.4h |
| September | Acceptable | 12° - 19° | 15° | 286 mm | overcast | 83% | 3.4 m/s | 1.2 high | 12.3h |
| October | Acceptable | 5° - 14° | 7° | 163 mm | partly cloudy | 83% | 3.7 m/s | 0.8 moderate | 11.1h |
| November | Good | -1° - 9° | 2° | 87 mm | partly cloudy | 82% | 3.4 m/s | 0.5 low | 10.1h |
| December | Acceptable | -5° - 4° | -5° | 44 mm | some cloud | 82% | 4.0 m/s | 0.3 low | 9.6h |
