Grannis, MT Weather Forecast
Local 7-day forecast
Sunny
Track current conditions, temperature changes, wind, and the full daily outlook for Grannis, MT in one place.
Sunny, with a high near 68. East northeast wind 2 to 18 mph.
Local Weather Overview
This forecast page for Grannis, MT is designed for quick trip planning, giving you a clean read on daytime highs, overnight lows, and changing conditions across the upcoming forecast window. Latest sync: Sep 14, 2026 9:22 PM MDT.
The active forecast window currently covers Sep 15 to Sep 21, 2026 for Grannis, MT.
Page Snapshot
- Page focus
- city weather
- Forecast window
- Sep 15 to Sep 21, 2026
- Latest sync
- Sep 14, 2026 9:22 PM MDT
- Forecast office
- BYZ
- Source
- NOAA / NWS
Daily Outlook
This Week in Grannis
Thursday looks like the warmest upcoming period in Grannis at 77 degrees F.
Tuesday Night is the coolest period ahead with temperatures near 40 degrees F.
The strongest winds are forecast for Wednesday Night at about 5 to 22 mph ESE.
Precipitation is mentioned in 6 upcoming forecast periods.
Forecast Details
- Last updated
- Sep 14, 2026 9:22 PM MDT
- Coverage
- 7 days
- Time zone
- America/Denver
- Forecast office
- BYZ
- Radar station
- KBLX
Weather data is provided by the National Weather Service and refreshed automatically for U.S. locations.
Open NOAA sourceExtended Forecast
Partly cloudy, with a low around 40. East wind 3 to 16 mph.
Sunny, with a high near 69. North northwest wind 2 to 12 mph.
Partly cloudy, with a low around 42. East southeast wind 5 to 22 mph.
A slight chance of showers and thunderstorms after noon. Mostly sunny. High near 77, with temperatures falling to around 74 in the afternoon. South southwest wind 1 to 6 mph. Chance of precipitation is 20%.
A chance of showers and thunderstorms. Mostly cloudy. Low around 48, with temperatures rising to around 50 overnight. South southwest wind 5 to 9 mph. Chance of precipitation is 40%.
A chance of rain showers before noon, then showers and thunderstorms likely. Partly sunny. High near 72, with temperatures falling to around 69 in the afternoon. West wind 3 to 8 mph. Chance of precipitation is 70%.
A chance of showers and thunderstorms. Mostly cloudy, with a low around 45. Southwest wind 3 to 9 mph. Chance of precipitation is 50%.
A chance of rain showers before noon, then a chance of showers and thunderstorms. Partly sunny. High near 69, with temperatures falling to around 67 in the afternoon. West wind 5 to 8 mph. Chance of precipitation is 40%.
A slight chance of showers and thunderstorms before midnight. Partly cloudy, with a low around 44. West southwest wind 6 to 9 mph. Chance of precipitation is 20%.
Sunny, with a high near 72. West wind 3 to 7 mph.
Mostly clear, with a low around 44. South wind 3 to 9 mph.
Sunny. High near 76, with temperatures falling to around 74 in the afternoon. West southwest wind around 6 mph.
Detailed Forecast
| Period | Conditions | Temp | Wind |
|---|---|---|---|
|
Tuesday
Sep 15
|
Sunny
|
68°F |
2 to 18 mph
ENE
|
|
Tuesday Night
Sep 15
|
Partly Cloudy
|
40°F |
3 to 16 mph
E
|
|
Wednesday
Sep 16
|
Sunny
|
69°F |
2 to 12 mph
NNW
|
|
Wednesday Night
Sep 16
|
Partly Cloudy
|
42°F |
5 to 22 mph
ESE
|
|
Thursday
Sep 17
|
Mostly Sunny then Slight Chance Showers And Thunderstorms
|
77°F |
1 to 6 mph
SSW
|
|
Thursday Night
Sep 17
|
Chance Showers And Thunderstorms
|
48°F |
5 to 9 mph
SSW
|
|
Friday
Sep 18
|
Showers And Thunderstorms Likely
|
72°F |
3 to 8 mph
W
|
|
Friday Night
Sep 18
|
Chance Showers And Thunderstorms
|
45°F |
3 to 9 mph
SW
|
|
Saturday
Sep 19
|
Chance Rain Showers
|
69°F |
5 to 8 mph
W
|
|
Saturday Night
Sep 19
|
Slight Chance Showers And Thunderstorms then Partly Cloudy
|
44°F |
6 to 9 mph
WSW
|
|
Sunday
Sep 20
|
Sunny
|
72°F |
3 to 7 mph
W
|
|
Sunday Night
Sep 20
|
Mostly Clear
|
44°F |
3 to 9 mph
S
|
|
Monday
Sep 21
|
Sunny
|
76°F |
6 mph
WSW
|
Nearby Forecasts
Explore weather pages for nearby cities and major places around Grannis.