Westby, Montana Weather
Pikas hayfeeding in granite peaks. Day 78 of spring. Read this microseason across nine climate regions →
Westby weather forecast — hour by hour, 7-day outlook, NOAA radar
- TodayJun 4Overcast15%—70°49°—
- FridayJun 5Rain10%0.22″83°53°+13°
- SaturdayJun 6Drizzle81%0.02″94°58°+11°
- SundayJun 7Drizzle81%—79°57°-15°
- MondayJun 8Overcast31%—76°51°-3°
- TuesdayJun 9Showers35%0.09″73°58°-3°
- WednesdayJun 10Light Drizzle35%—76°58°+3°
AQI 38 (Good), driven by Ozone. AQI up 8 over the last 6 hours (gradual rise). Ozone at AQI 33 now. With UV 0.1 peaking around 1 PM under clear skies, surface ozone likely climbs to AQI 8 by mid-afternoon.
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 33 now. With UV 0.1 peaking around 1 PM under clear skies, surface ozone likely climbs to AQI 8 by mid-afternoon.
- Present
- AQI 33
- UV peak
- 0.1 at 1 PM
- Sky at peak
- clear
- Projected peak
- AQI 8
PM × Wind × Precip
PM2.5 at 4.8 µg/m³ (AQI 27) with a 0.86 fine-to-coarse ratio and 3 mph wind — combustion smoke trapped in calm air, not road dust.
- PM2.5/PM10
- 0.86
- Wind
- calm
- Recent rain
- 0h in last 6h
- Pattern
- stagnant smoke
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).
The higher the clouds, the finer the weather.
- Moonrise
- 6:25 AM
- Moonset
- 3:41 PM
- In sign
- ♒︎ Aquarius
Pikas hayfeeding in granite peaks
Westby at a glance
- Today vs. normal: 65°F — typical for the season
- Last frost: June 8 (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
Warm-season window is open
As of June 5, the last spring frost has passed for most years. Transplant tomatoes, peppers, eggplants, basil, and cucurbits (cucumbers, squash, melons) now. Direct-sow beans and corn into warm soil.
SPC Convective Outlook
Storm Prediction Center — Westby
SPC has placed Westby in the Slight Risk category for severe thunderstorms day after tomorrow.
- TODAYTSTMGeneral Thunderstorms
- TOMORROWNONENo severe risk
- DAY 3SLGTSlight Risk
Scattered severe storms possible. A few tornadoes, hail, and damaging wind gusts possible.
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.