Big Arm, MT Weather Forecast
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Big Arm Weather Forecast
| TONIGHT | MONDAY | MONDAY NIGHT | TUESDAY | TUESDAY NIGHT | WEDNESDAY | WEDNESDAY NIGHT | THURSDAY | THURSDAY NIGHT | FRIDAY | FRIDAY NIGHT | SATURDAY |
| Mostly Cloudy | Mostly Cloudy | Rain and Snow | Snow | Rain | Rain and Snow | Rain and Snow | Rain and Snow | Rain and Snow | Chance of Snow | Rain and Snow | Mostly Cloudy |
| Lo: 25°FLo: -4°C | Hi: 50°FHi: 10°C | Lo: 26°FLo: -3°C | Hi: 45°FHi: 7°C | Lo: 26°FLo: -3°C | Hi: 46°FHi: 8°C | Lo: 25°FLo: -4°C | Hi: 45°FHi: 7°C | Lo: 22°FLo: -6°C | Hi: 45°FHi: 7°C | Lo: 21°FLo: -6°C | Hi: 46°FHi: 8°C |
| POP: 90% | POP: 90% | POP: 70% | POP: 80% | POP: 80% | POP: 40% | POP: 30% | POP: 20% | POP: 20% |
POP = Probability of Precipitation.
Weather Outlook Updated: 1228 PM MDT Sun Oct 25 2026 

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Issued: 1247 PM MDT Sun Oct 25 2026
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KEY MESSAGES:- High pressure breaks down early Monday.
- Colder temperatures and periods of rain and mountain snow expected this week.
A weak ridge of high pressure over the Northern Rockies will maintain dry conditions and seasonal temperatures through this afternoon. Patchy fog is possible Monday morning, but it is not expected to be as dense or widespread as Sunday morning`s fog.
A low pressure system will move into the Pacific Northwest on Monday. Rain and mountain snow from this sys...
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