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Arrowhead Lake Weather Forecast
| REST OF TODAY | TONIGHT | TUESDAY | TUESDAY NIGHT | WEDNESDAY | WEDNESDAY NIGHT | THURSDAY | THURSDAY NIGHT | FRIDAY | FRIDAY NIGHT | SATURDAY | SATURDAY NIGHT |
 |  | |  |  | | | | | |  |  |
| Sunny | Mostly Clear | Mostly Sunny | Chance of T-Storm | Patchy Fog | Mostly Clear | Sunny | Mostly Clear | Sunny | Mostly Clear | Rain Showers | Partly Cloudy |
| Hi: 69°FHi: 21°C | Lo: 31°FLo: -1°C | Hi: 69°FHi: 21°C | Lo: 35°FLo: 2°C | Hi: 65°FHi: 18°C | Lo: 35°FLo: 2°C | Hi: 71°FHi: 22°C | Lo: 39°FLo: 4°C | Hi: 71°FHi: 22°C | Lo: 39°FLo: 4°C | Hi: 65°FHi: 18°C | Lo: 35°FLo: 2°C |
| POP: 60% | POP: 20% |
POP = Probability of Precipitation.
Weather Outlook Updated: 1238 PM MDT Mon Sep 21 2026 
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Issued: 134 PM MDT Mon Sep 21 2026
Key Messages
- Warmer and drier much of the work week. 80s return midweek.
- Scattered showers and storms late Tuesday into Wednesday.
Discussion
...
Rest of Today through Sunday...
Low clouds continue to clear over southeast Montana and portions of northern Wyoming this afternoon. Ridging will generally take over the pattern this week, bringing warmer and mostly dry conditions.
HiRes models show patchy fog developing along and north of I-90 from Billings to Livingston tonight. Coverage and density are ex...