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Weather & Climate in Iiyama, Japan
Temperature, precipitation, air quality, natural hazards, and monthly weather data.
Iiyama experiences four distinct seasons with an average annual temperature of 50°F (10°C). Winters average 27°F in January while summers reach 71°F in July. The area gets 223 sunny days per year, above the national average. Annual precipitation totals 62.5 inches (wetter than the 38-inch national average). The area receives 18.5 inches of snow annually, a moderate snowfall amount. The city sits at an elevation of 1,020 feet.
Temperature
27°F Jan (-3°C)
71°F Jul (22°C)
| Annual Average | 49.6°F |
| 8% below US avg | |
| January Average | 27°F (-3°C) |
| July Average | 71°F (22°C) |
| Sunny Days | 223 days/yr |
Geography
| Elevation | 1,020 ft (311 m) |
| Area | 78.2 sq mi (202.4 km²) |
| Population Density | 257/sq mi |
| Coordinates | 36.8500°N, 138.3667°W |
| Timezone | Asia/Tokyo |
Precipitation & Snow
Air Quality
Earthquake History
711 earthquakes (M2.5+) recorded within 150 km since 1990. Strongest on record: M7.5.
| Jan 1, 2024 | 2024 Noto Peninsula, Japan Earthquake | M7.5 | 120 km | 10 km |
| Jul 16, 2007 | 20 km NNW of Kashiwazaki, Japan | M6.6 | 77 km | 12 km |
| Feb 7, 1993 | 69 km NNE of Nanao, Japan | M6.6 | 132 km | 11 km |
| May 5, 2023 | 49 km NE of Anamizu, Japan | M6.2 | 122 km | 10 km |
| Jan 1, 2024 | 8 km SW of Anamizu, Japan | M6.2 | 142 km | 10 km |
| Mar 11, 2011 | 13 km E of Arai, Japan | M6.2 | 18 km | 9 km |
| Jan 9, 2024 | 53 km WSW of Sado, Japan | M5.9 | 124 km | 10 km |
| Jan 1, 2024 | 42 km NE of Anamizu, Japan | M5.8 | 122 km | 10 km |
| Apr 16, 2011 | 6 km ENE of Tanuma, Japan | M5.8 | 126 km | 77 km |
| Feb 25, 2013 | 29 km NE of Numata, Japan | M5.8 | 78 km | 10 km |
| Mar 11, 2011 | eastern Honshu, Japan | M5.7 | 12 km | 12 km |
| Dec 3, 1996 | 35 km SE of Muramatsu, Japan | M5.7 | 121 km | 139 km |
| Jul 16, 2007 | 16 km NNW of Kashiwazaki, Japan | M5.7 | 73 km | 15 km |
| Jun 2, 2024 | 40 km NE of Anamizu, Japan | M5.7 | 118 km | 9 km |
| Jan 1, 2024 | 54 km NE of Anamizu, Japan | M5.6 | 113 km | 10 km |
| May 5, 2023 | 43 km NE of Anamizu, Japan | M5.6 | 120 km | 10 km |
| Jan 1, 2024 | 7 km N of Anamizu, Japan | M5.6 | 140 km | 10 km |
| Jan 1, 2024 | 56 km NE of Anamizu, Japan | M5.5 | 113 km | 10 km |
| Apr 11, 2011 | 8 km WSW of Iiyama, Japan | M5.5 | 9 km | 17 km |
| Mar 15, 2012 | 3 km ENE of ?me, Japan | M5.5 | 142 km | 104 km |
Source: USGS Earthquake Catalog (M2.5+, 1990–2025). Sorted by magnitude.
Hurricane History
27 hurricanes (Category 1+) recorded within 500 km since 1980. Strongest on record: Category 3.
| Year | Name | Category | Max Wind | Closest |
| 2019 | Faxai | Category 2 | 92 mph | 204 km |
| 2019 | Hagibis | Category 1 | 92 mph | 167 km |
| 2018 | Jebi | Category 1 | 86 mph | 165 km |
| 2018 | Jongdari | Category 1 | 81 mph | 285 km |
| 2014 | Phanfone | Category 1 | 75 mph | 217 km |
| 2011 | Roke | Category 1 | 92 mph | 129 km |
| 2007 | Fitow | Category 1 | 75 mph | 158 km |
| 2005 | Mawar | Category 2 | 81 mph | 212 km |
| 2004 | Ma-on | Category 3 | 92 mph | 189 km |
| 2004 | Songda | Category 1 | 75 mph | 299 km |
| 2004 | Chaba | Category 1 | 69 mph | 216 km |
| 2003 | Etau | Category 1 | 58 mph | 239 km |
| 2002 | Higos | Category 2 | 86 mph | 173 km |
| 2001 | Danas | Category 1 | 69 mph | 180 km |
| 2000 | Kirogi | Category 1 | 81 mph | 265 km |
| 1998 | Vicki | Category 2 | 69 mph | 79 km |
| 1998 | Zeb | Category 1 | 58 mph | 241 km |
| 1998 | Stella | Category 1 | 69 mph | 139 km |
| 1996 | Kirk | Category 1 | 63 mph | 177 km |
| 1995 | Ryan | Category 1 | 40 mph | 271 km |
Source: NOAA IBTrACS (Category 1+, 1980–2026).
Tsunami History
13 tsunamis recorded within 500 km. Highest wave on record: 11.3 m (37 ft).
| Year | Location | Cause | Max Wave | Deaths | Distance |
| 2024 | HONSHU: W COAST | Eruption + Earthquake | 11.3 m | 549 | 120 km |
| 1993 | HONSHU ISLAND | Earthquake | 0.5 m | — | 132 km |
| 1987 | HONSHU ISLAND | Earthquake | 0.2 m | — | 80 km |
| 2023 | NOTO PENINSULA, JAPAN | Earthquake | 0.1 m | 1 | 121 km |
| 2007 | HONSHU: W COAST | Earthquake | — | 15 | 81 km |
| 1892 | SW. HONSHU ISLAND | Earthquake | — | 1 | 140 km |
| 1802 | NW. HONSHU ISLAND | Earthquake | — | 19 | 95 km |
| 1762 | NW. HONSHU ISLAND | Earthquake | — | — | 142 km |
| 1751 | NW. HONSHU ISLAND | Eruption + Earthquake | — | 2,100 | 46 km |
| 1614 | NIIGATA PREFECTURE | Earthquake | — | — | 79 km |
| 1448 | SADO, JAPAN | Earthquake | — | — | 74 km |
| 887 | NIIGATA | Earthquake | — | 2,000 | 76 km |
| 863 | NW. HONSHU ISLAND | Eruption + Earthquake | — | — | 43 km |
Source: NOAA/NCEI Historical Tsunami Database.
Nearby Volcanoes
15 volcanoes within 200 km. Closest: Shiga (23 km).
| Name | Type | Elevation | Last Eruption | Distance |
| Shiga | Shield(s) | 2,041 m (6,696 ft) | Unknown | 23 km |
| Myokosan | Stratovolcano | 2,454 m (8,051 ft) | -750 | 23 km |
| Kusatsu-Shiranesan | Stratovolcano(es) | 2,165 m (7,103 ft) | 2018 | 30 km |
| Niigata-Yakeyama | Lava dome | 2,400 m (7,874 ft) | 1998 | 31 km |
| Asamayama | Complex | 2,568 m (8,425 ft) | 2019 | 51 km |
| Harunasan | Stratovolcano | 1,449 m (4,754 ft) | 550 | 60 km |
| Midagahara | Stratovolcano | 2,621 m (8,599 ft) | 1839 | 76 km |
| Akagisan | Stratovolcano | 1,828 m (5,997 ft) | Unknown | 80 km |
| Hiuchigatake | Stratovolcano | 2,356 m (7,730 ft) | 1544 | 83 km |
| Washiba-Kumonotaira | Shield(s) | 2,924 m (9,593 ft) | Unknown | 85 km |
| Yokodake | Stratovolcano(es) | 2,480 m (8,136 ft) | 1200 | 85 km |
| Nikko-Shiranesan | Shield | 2,578 m (8,458 ft) | 1952 | 90 km |
| Yakedake | Stratovolcano(es) | 2,455 m (8,054 ft) | 1995 | 98 km |
| Nantaisan | Stratovolcano | 2,486 m (8,156 ft) | -9540 | 101 km |
| Omanago Group | Lava dome(s) | 2,341 m (7,680 ft) | -3050 | 102 km |
Source: Smithsonian Institution Global Volcanism Program (GVP).
Monthly Weather
| Month | Avg Temperature | Precipitation | Summary |
|---|---|---|---|
| January | 27°F (-3°C) | 5.4 in | Coldest |
| February | 27°F (-3°C) | 4.3 in | |
| March | 33°F (1°C) | 3.8 in | |
| April | 46°F (8°C) | 3.7 in | Driest |
| May | 57°F (14°C) | 4.0 in | |
| June | 64°F (18°C) | 6.1 in | |
| July | 71°F (22°C) | 7.3 in | Wettest |
| August | 74°F (23°C) | 6.0 in | Warmest |
| September | 65°F (19°C) | 7.2 in | |
| October | 54°F (12°C) | 5.2 in | |
| November | 44°F (6°C) | 4.5 in | |
| December | 33°F (1°C) | 5.0 in |
Iiyama has a seasonal temperature swing of 47°F / from 27°F in January to 74°F in August. Total annual precipitation is 62.5 inches, with July being the wettest month (7.3") and April the driest (3.7").