Weather World
Arrowhead Lake, MT Weather Forecast
Quick Weather Clicks
Settings
Sun & Moon
Arrowhead Lake Weather Forecast
| REST OF TODAY | TONIGHT | SATURDAY | SATURDAY NIGHT | SUNDAY | SUNDAY NIGHT | MONDAY | MONDAY NIGHT | TUESDAY | TUESDAY NIGHT | WEDNESDAY | WEDNESDAY NIGHT |
 |  |  | | |  | |  | | |  |  |
| Thunderstorms | Chance of T-Storm | Chance of T-Storm | Chance of T-Storm | Chance of T-Storm | Patchy Fog | Patchy Fog | Partly Cloudy | Chance of T-Storm | Partly Cloudy | Mostly Sunny | Mostly Clear |
| Hi: 69°FHi: 21°C | Lo: 39°FLo: 4°C | Hi: 59°FHi: 15°C | Lo: 35°FLo: 2°C | Hi: 59°FHi: 15°C | Lo: 31°FLo: -1°C | Hi: 65°FHi: 18°C | Lo: 31°FLo: -1°C | Hi: 69°FHi: 21°C | Lo: 35°FLo: 2°C | Hi: 69°FHi: 21°C | Lo: 35°FLo: 2°C |
| POP: 90% | POP: 90% | POP: 80% | POP: 70% | POP: 60% | POP: 20% |
POP = Probability of Precipitation.
Weather Outlook Updated: 703 AM MDT Fri Sep 18 2026 
Arrowhead Lake Radar Loop
Use the map search tool if you want to place a location marker on the radar map...
Arrowhead Lake Weather Map
Arrowhead Lake Quick Facts
Arrowhead Lake Forecast Discussion
Meteorlogic Glosserator
Instant definitions for any meteorological term.
Instant definitions for any meteorological term.
Issued: 538 AM MDT Fri Sep 18 2026
Key Messages
- A few strong thunderstorms are possible, mainly around and east of Billings this afternoon and evening.
- Flood Watch tonight through Sunday for much of the area. Widespread precipitation this afternoon through the weekend, with the potential for locally heavy rainfall widespread through Saturday night.
- Chance for at least an inch of rainfall is greater than 80 percent across much of southern Montana and northern Wyoming. The chance for at least 2 inches of rainfall is 50 to 80 percent...