Sumas, Washington Weather
Rufous Hummingbirds Arrive. Day 77 of spring. Read this microseason across nine climate regions →
Sumas weather forecast — hour by hour, 7-day outlook, NOAA radar
- TodayJun 3Overcast——73°58°—
- ThursdayJun 4Overcast27%—64°56°-9°
- FridayJun 5Light Showers88%0.60″58°47°-6°
- SaturdayJun 6Drizzle71%0.22″57°45°-1°
- SundayJun 7Drizzle14%—63°46°+6°
- MondayJun 8Light Drizzle61%0.03″67°47°+4°
- TuesdayJun 9Light Drizzle51%—57°48°-10°
PM2.5/PM10 ratio 0.66 with 11 mph wind — characteristic of long-range haze transport rather than a local source. AQI up 9 over the last 6 hours (gradual rise).
OK No precautions needed for the general population; unusually sensitive individuals may consider limiting prolonged outdoor exertion.
What's driving it
Ozone × UV × Sky
Ozone at AQI 43 now. With UV 0.2 peaking around 1 PM under partly cloudy skies, surface ozone likely climbs to AQI 7 by mid-afternoon.
- Present
- AQI 43
- UV peak
- 0.2 at 1 PM
- Sky at peak
- partly cloudy
- Projected peak
- AQI 7
PM × Wind × Precip
PM2.5/PM10 ratio 0.66 with 11 mph wind — characteristic of long-range haze transport rather than a local source.
- PM2.5/PM10
- 0.66
- Wind
- breezy
- Recent rain
- 0h in last 6h
- Pattern
- transport
Trends
Seven days of AQI and PM2.5.
Hourly air-quality data from the Copernicus Atmosphere Monitoring Service, charted across the past and next several days. Dashed lines mark the AQI breakpoints at 50 (Good → Moderate) and 100 (Moderate → Unhealthy for Sensitive Groups).
A summer fog for fair, a winter fog for rain.
- Moonrise
- 7:16 AM
- Moonset
- 3:44 PM
- In sign
- ♑︎ Capricorn
Rufous Hummingbirds Arrive
Sumas at a glance
- Today vs. normal: 68°F — typical for the season
- Last frost: June 9 (climatological average for this latitude)
- Microseason: Jun 1–5
- Planting window: Harvest spring lettuce before it bolts. Sow heat-tolerant greens.
Right now in the garden
Peak growing season
As of June 4, the growing season is at its peak — frost is months away. Continue succession-planting beans and summer squash. Start fall brassicas (broccoli, cabbage, kale) from seed indoors for transplanting in late summer.
SPC Convective Outlook
Storm Prediction Center — Sumas
SPC has placed Sumas in the General Thunderstorms category for severe thunderstorms day after tomorrow.
- TODAYNONENo severe risk
- TOMORROWNONENo severe risk
- DAY 3TSTMGeneral Thunderstorms
Thunderstorms possible. Not severe, but capable of producing lightning and brief heavy rain.
Source: NOAA / NWS Storm Prediction Center categorical convective outlook. Outlooks are re-issued multiple times per day; this page reflects the most recent SPC polygons covering the city’s coordinates.