All Countries
Weather & Climate in Semiahmoo, BC
Temperature, precipitation, air quality, natural hazards, and monthly weather data.
Semiahmoo experiences four distinct seasons with an average annual temperature of 50°F (10°C). Winters average 37°F in January while summers reach 64°F in July. The area gets 227 sunny days per year, above the national average. Annual precipitation totals 60.2 inches (wetter than the 38-inch national average). The city sits at an elevation of 141 feet.
Temperature
37°F Jan (3°C)
64°F Jul (18°C)
| Annual Average | 50.3°F |
| 7% below US avg | |
| January Average | 37°F (3°C) |
| July Average | 64°F (18°C) |
| Sunny Days | 227 days/yr |
Geography
| Elevation | 141 ft (43 m) |
| Area | 0.5 sq mi (1.3 km²) |
| Population Density | 139/sq mi |
| Coordinates | 49.0108°N, 122.7650°W |
| Timezone | America/Vancouver |
Precipitation & Snow
Air Quality
Earthquake History
381 earthquakes (M2.5+) recorded within 150 km since 1990. Strongest on record: M5.0.
| Apr 14, 1990 | 4 km ENE of Deming, Washington | M5.0 | 48 km | 12 km |
| Feb 21, 2025 | 28 km W of Squamish, Canada | M4.8 | 95 km | 10 km |
| Jan 30, 2009 | 6 km ESE of Lofall, Washington | M4.7 | 137 km | 62 km |
| Jul 12, 2019 | 2 km S of Roosevelt, Washington | M4.6 | 138 km | 29 km |
| Mar 3, 2025 | 2025 Orcas Island, Washington | M4.5 | 45 km | 16 km |
| Jun 24, 1997 | 19 km SSW of Gibsons, Canada | M4.4 | 67 km | 3 km |
| Apr 2, 1990 | 2 km ENE of Deming, Washington | M4.3 | 47 km | 0 km |
| Feb 19, 1991 | 31 km E of Squamish, Canada | M4.3 | 76 km | 5 km |
| Feb 22, 1996 | 31 km NNE of South Pender Harbour, Canada | M4.1 | 128 km | 2 km |
| Sep 21, 2002 | 9 km SW of Friday Harbor, Washington | M4.1 | 64 km | 23 km |
| Apr 3, 1990 | 3 km ENE of Deming, Washington | M4.0 | 47 km | 1 km |
| Apr 14, 1990 | 2 km ESE of Deming, Washington | M4.0 | 47 km | 3 km |
| Dec 27, 2012 | 12 km E of North Saanich, Canada | M4.0 | 53 km | 54 km |
| Sep 26, 2024 | 12 km E of Saanichton, Canada | M4.0 | 60 km | 52 km |
| Jul 1, 2009 | 4 km SE of Coupeville, Washington | M4.0 | 91 km | 58 km |
| Apr 7, 2001 | 36 km NNW of Neah Bay, Washington | M3.9 | 149 km | 32 km |
| Mar 6, 2025 | 14 km SW of Blyn, Washington | M3.9 | 124 km | 42 km |
| Jul 24, 2011 | 21 km W of Brinnon, Washington | M3.9 | 148 km | 41 km |
| Mar 17, 2004 | 3 km SW of Clear Lake, Washington | M3.8 | 73 km | 0 km |
| Sep 8, 2022 | 7 km WNW of Lofall, Washington | M3.7 | 130 km | 23 km |
Source: USGS Earthquake Catalog (M2.5+, 1990–2025). Sorted by magnitude.
Tsunami History
3 tsunamis recorded within 500 km. Highest wave on record: 38.0 m (125 ft).
| Year | Location | Cause | Max Wave | Deaths | Distance |
| 2007 | CHEHALIS LAKE, CHILLIWACK | Meteorological | 38.0 m | — | 75 km |
| 1891 | WASHINGTON | Eruption + Earthquake | 2.4 m | — | 125 km |
| 1820 | CAMANO ISLAND, WA | Meteorological | — | — | 110 km |
Source: NOAA/NCEI Historical Tsunami Database.
Nearby Volcanoes
6 volcanoes within 200 km. Closest: Baker (74 km).
| Name | Type | Elevation | Last Eruption | Distance |
| Baker | Stratovolcano(es) | 3,285 m (10,778 ft) | 1880 | 74 km |
| Garibaldi | Stratovolcano | 2,678 m (8,786 ft) | -8060 | 95 km |
| Garibaldi Lake | Volcanic field | 2,316 m (7,598 ft) | Unknown | 104 km |
| Cayley Volcanic Field | Volcanic field | 2,375 m (7,792 ft) | Unknown | 129 km |
| Glacier Peak | Stratovolcano | 3,213 m (10,541 ft) | 1700 | 157 km |
| Meager | Complex | 2,680 m (8,793 ft) | -410 | 188 km |
Source: Smithsonian Institution Global Volcanism Program (GVP).
Wildfire History
3 wildfires (100+ acres) recorded within 100 km. Largest: COPPER LAKE (3,825 acres, 2022).
| Year | Name | Acres Burned | Distance |
| 2022 | COPPER LAKE | 3,825 | 98 km |
| 2022 | SILESIA | 2,737 | 92 km |
| 2022 | LITTLE CHILL | 2,242 | 95 km |
Source: NIFC/IRWIN Wildfire Records (100+ acres).
Monthly Weather
| Month | Avg Temperature | Precipitation | Summary |
|---|---|---|---|
| January | 37°F (3°C) | 8.3 in | Coldest |
| February | 40°F (5°C) | 5.7 in | |
| March | 44°F (7°C) | 5.2 in | |
| April | 49°F (10°C) | 4.5 in | |
| May | 55°F (13°C) | 3.7 in | |
| June | 60°F (16°C) | 3.1 in | |
| July | 64°F (18°C) | 2.1 in | Driest |
| August | 65°F (18°C) | 2.1 in | Warmest |
| September | 59°F (15°C) | 2.8 in | |
| October | 51°F (10°C) | 5.8 in | |
| November | 43°F (6°C) | 9.4 in | Wettest |
| December | 37°F (3°C) | 7.6 in |
Semiahmoo has a seasonal temperature swing of 28°F / from 37°F in January to 65°F in August. Total annual precipitation is 60.3 inches, with November being the wettest month (9.4") and July the driest (2.1").