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Weather & Climate in Ryōgoku, Japan
Temperature, precipitation, air quality, natural hazards, and monthly weather data.
Ryōgoku enjoys a temperate climate with an average annual temperature of 58°F (15°C). Winters average 39°F in January while summers reach 75°F in July. The area gets 234 sunny days per year, above the national average. Annual precipitation totals 56.2 inches (wetter than the 38-inch national average). The city sits at an elevation of 144 feet.
Temperature
39°F Jan (4°C)
75°F Jul (24°C)
| Annual Average | 58.4°F |
| 8% above US avg | |
| January Average | 39°F (4°C) |
| July Average | 75°F (24°C) |
| Sunny Days | 234 days/yr |
Geography
| Elevation | 144 ft (44 m) |
| Area | 30.1 sq mi (77.9 km²) |
| Population Density | 1,655/sq mi |
| Coordinates | 35.7167°N, 140.3667°W |
| Timezone | Asia/Tokyo |
Precipitation & Snow
Air Quality
Earthquake History
3,491 earthquakes (M2.5+) recorded within 150 km since 1990. Strongest on record: M7.9.
| Mar 11, 2011 | 47 km E of ?arai, Japan | M7.9 | 92 km | 43 km |
| May 7, 2008 | 78 km NE of Hasaki, Japan | M6.9 | 116 km | 27 km |
| Apr 11, 2011 | 17 km SSW of Ishikawa, Japan | M6.6 | 143 km | 11 km |
| Mar 11, 2011 | 81 km NE of Hasaki, Japan | M6.5 | 119 km | 7 km |
| Jun 1, 1990 | near the east coast of Honshu, Japan | M6.3 | 22 km | 67 km |
| Jul 30, 2011 | 13 km SSE of Iwaki, Japan | M6.3 | 146 km | 38 km |
| Mar 11, 2011 | 92 km ENE of Hasaki, Japan | M6.3 | 134 km | 21 km |
| Apr 21, 2011 | 6 km WNW of T?gane, Japan | M6.2 | 16 km | 43 km |
| Sep 11, 1996 | 23 km SSE of Hasaki, Japan | M6.2 | 56 km | 55 km |
| Apr 11, 2011 | 23 km SE of T?gane, Japan | M6.2 | 38 km | 15 km |
| May 7, 2008 | 80 km NE of Hasaki, Japan | M6.2 | 118 km | 19 km |
| Mar 11, 2011 | 70 km ESE of Kitaibaraki, Japan | M6.2 | 138 km | 40 km |
| Jun 3, 2000 | 6 km SE of Narut?, Japan | M6.2 | 20 km | 62 km |
| May 7, 2008 | 95 km ENE of Hasaki, Japan | M6.1 | 134 km | 23 km |
| May 26, 2023 | 12 km SE of Narutō, Japan | M6.1 | 25 km | 42 km |
| Mar 13, 2011 | 72 km E of Hasaki, Japan | M6.1 | 115 km | 8 km |
| Sep 15, 2011 | 68 km E of ?arai, Japan | M6.1 | 106 km | 28 km |
| Jun 5, 2012 | 75 km ESE of ?hara, Japan | M6.1 | 111 km | 15 km |
| Aug 5, 1990 | 43 km E of ?arai, Japan | M6.1 | 92 km | 27 km |
| Jul 20, 2000 | 31 km ESE of Hitachi, Japan | M6.0 | 104 km | 47 km |
Source: USGS Earthquake Catalog (M2.5+, 1990–2025). Sorted by magnitude.
Hurricane History
41 hurricanes (Category 1+) recorded within 500 km since 1980. Strongest on record: Category 3.
| Year | Name | Category | Max Wind | Closest |
| 2025 | Nakri | Category 1 | — | 267 km |
| 2024 | Ampil | Category 3 | 98 mph | 168 km |
| 2024 | Jebi | Category 1 | 75 mph | 195 km |
| 2021 | Mindulle | Category 1 | 86 mph | 265 km |
| 2019 | Faxai | Category 3 | 98 mph | 11 km |
| 2019 | Hagibis | Category 2 | 92 mph | 88 km |
| 2018 | Jongdari | Category 2 | 86 mph | 210 km |
| 2018 | Shanshan | Category 1 | 81 mph | 122 km |
| 2016 | Mindulle | Category 1 | 75 mph | 176 km |
| 2016 | Lionrock | Category 1 | 81 mph | 202 km |
| 2014 | Phanfone | Category 1 | 75 mph | 200 km |
| 2011 | Roke | Category 1 | 92 mph | 107 km |
| 2009 | Krovanh | Category 1 | 69 mph | 250 km |
| 2007 | Fitow | Category 1 | 81 mph | 106 km |
| 2005 | Saola | Category 2 | 86 mph | 231 km |
| 2005 | Mawar | Category 2 | 81 mph | 6 km |
| 2004 | Ma-on | Category 3 | 92 mph | 53 km |
| 2003 | Choi-wan | Category 3 | 81 mph | 250 km |
| 2002 | Higos | Category 2 | 86 mph | 47 km |
| 2002 | Phanfone | Category 1 | 75 mph | 275 km |
Source: NOAA IBTrACS (Category 1+, 1980–2026).
Tsunami History
20 tsunamis recorded within 500 km. Highest wave on record: 13.0 m (43 ft).
| Year | Location | Cause | Max Wave | Deaths | Distance |
| 1923 | SAGAMI BAY | Earthquake | 13.0 m | 105,385 | 104 km |
| 1703 | OFF SW BOSO PENINSULA | Earthquake | 11.7 m | 5,233 | 124 km |
| 1677 | OFF SE. BOSO PENINSULA | Earthquake | 8.0 m | 500 | 130 km |
| 1495 | KAMAKURA, SAGAMI BAY, TOKAIDO | Earthquake | 5.0 m | 200 | 104 km |
| 1732 | KUJUKURI BEACH, JAPAN | Earthquake | 2.0 m | — | 70 km |
| 1670 | BOSO, JAPAN | Earthquake | 2.0 m | — | 62 km |
| 1433 | OFF IZU-OSHIMA | Earthquake | 2.0 m | — | 120 km |
| 1938 | JAPAN TRENCH | Earthquake | 0.8 m | — | 143 km |
| 1980 | HONSHU ISLAND | Earthquake | 0.6 m | — | 148 km |
| 1982 | IBARAKI, JAPAN | Earthquake | 0.4 m | — | 131 km |
| 1961 | KASHIMA, JAPAN | Earthquake | 0.4 m | — | 148 km |
| 1961 | KASHIMA, JAPAN | Earthquake | 0.4 m | — | 142 km |
| 1923 | KASHIMA, JAPAN | Earthquake | 0.4 m | — | 134 km |
| 1978 | TOKAIDO | Earthquake | 0.4 m | 25 | 143 km |
| 1923 | RYUKYU ISLANDS | Earthquake | 0.3 m | — | 92 km |
| 1896 | KASHIMA, JAPAN | Earthquake | 0.3 m | — | 104 km |
| 1935 | JAPAN | Earthquake | 0.2 m | — | 135 km |
| 1855 | TOKAIDO | Earthquake | — | 6,757 | 52 km |
| 1782 | ODAWARA, SAGAMI BAY | Eruption + Earthquake | — | — | 91 km |
| 1642 | BOSO, JAPAN | Earthquake | — | — | 61 km |
Source: NOAA/NCEI Historical Tsunami Database.
Nearby Volcanoes
15 volcanoes within 200 km. Closest: Hakoneyama (133 km).
| Name | Type | Elevation | Last Eruption | Distance |
| Hakoneyama | Complex | 1,438 m (4,718 ft) | 2015 | 133 km |
| Nantaisan | Stratovolcano | 2,486 m (8,156 ft) | -9540 | 141 km |
| Akagisan | Stratovolcano | 1,828 m (5,997 ft) | Unknown | 141 km |
| Izu-Oshima | Stratovolcano | 758 m (2,487 ft) | 1990 | 141 km |
| Takaharayama | Stratovolcano | 1,795 m (5,889 ft) | -4570 | 142 km |
| Omanago Group | Lava dome(s) | 2,341 m (7,680 ft) | -3050 | 143 km |
| Izu-Tobu | Pyroclastic cone(s) | 1,406 m (4,613 ft) | 1989 | 147 km |
| Nikko-Shiranesan | Shield | 2,578 m (8,458 ft) | 1952 | 150 km |
| Fujisan | Stratovolcano | 3,776 m (12,388 ft) | 1708 | 154 km |
| Harunasan | Stratovolcano | 1,449 m (4,754 ft) | 550 | 160 km |
| Nasudake | Stratovolcano(es) | 1,915 m (6,283 ft) | 1963 | 161 km |
| Toshima | Stratovolcano | 508 m (1,667 ft) | -4550 | 166 km |
| Hiuchigatake | Stratovolcano | 2,356 m (7,730 ft) | 1544 | 168 km |
| Niijima | Lava dome(s) | 432 m (1,417 ft) | 886 | 178 km |
| Asamayama | Complex | 2,568 m (8,425 ft) | 2019 | 183 km |
Source: Smithsonian Institution Global Volcanism Program (GVP).
Monthly Weather
| Month | Avg Temperature | Precipitation | Summary |
|---|---|---|---|
| January | 39°F (4°C) | 2.1 in | Coldest, Driest |
| February | 41°F (5°C) | 2.8 in | |
| March | 46°F (8°C) | 4.3 in | |
| April | 56°F (13°C) | 4.7 in | |
| May | 64°F (18°C) | 4.8 in | |
| June | 69°F (21°C) | 6.5 in | |
| July | 75°F (24°C) | 5.0 in | |
| August | 78°F (26°C) | 5.1 in | Warmest |
| September | 73°F (23°C) | 7.7 in | Wettest |
| October | 63°F (17°C) | 7.3 in | |
| November | 53°F (12°C) | 3.9 in | |
| December | 44°F (7°C) | 2.1 in |
Ryōgoku has a seasonal temperature swing of 39°F / from 39°F in January to 78°F in August. Total annual precipitation is 56.2 inches, with September being the wettest month (7.7") and January the driest (2.1").