National Weather Service Forecast for: Lewistown MT
Issued by: National Weather Service Great Falls, MT
Updated: 1:52 am MDT Jun 30, 2026
 
Overnight

Overnight: A 30 percent chance of showers, mainly before 5am. Cloudy, with a steady temperature around 54. West wind around 17 mph, with gusts as high as 28 mph.
Chance
Showers

 Tuesday

Tuesday: Mostly cloudy, then gradually becoming sunny, with a high near 71. West northwest wind 8 to 17 mph, with gusts as high as 28 mph.
Decreasing
Clouds

 Tuesday
Night
Tuesday Night: Partly cloudy, with a low around 46. West northwest wind 5 to 7 mph becoming calm in the evening.
Partly Cloudy

 Wednesday

Wednesday: Showers and thunderstorms likely, mainly before 4pm. Increasing clouds, with a high near 73. Light and variable wind. Chance of precipitation is 60%.
Mostly Sunny
then Showers
Likely
 Wednesday
Night
Wednesday Night: A chance of showers and thunderstorms. Mostly cloudy, with a low around 46. Light and variable wind. Chance of precipitation is 50%.
Chance
T-storms then
Slight Chance
Showers
 Thursday

Thursday: A 30 percent chance of showers and thunderstorms after noon. Mostly sunny, with a high near 76. Calm wind becoming west around 5 mph in the afternoon.
Mostly Sunny
then Chance
Showers
 Thursday
Night
Thursday Night: A slight chance of showers and thunderstorms before 9pm, then a slight chance of showers between 9pm and midnight. Partly cloudy, with a low around 48. Light and variable wind. Chance of precipitation is 20%.
Slight Chance
T-storms then
Partly Cloudy
 Friday

Friday: Showers likely and possibly a thunderstorm after noon. Partly sunny, with a high near 76. Light and variable wind.
Partly Sunny
then Showers
Likely
 Friday
Night
Friday Night: A chance of showers and thunderstorms before midnight. Mostly cloudy, with a low around 47.
Chance
T-storms then
Partly Cloudy
Lo 54 °F Hi 71 °F Lo 46 °F Hi 73 °F Lo 46 °F Hi 76 °F Lo 48 °F Hi 76 °F Lo 47 °F

 

Overnight
 
 A 30 percent chance of showers, mainly before 5am. Cloudy, with a steady temperature around 54. West wind around 17 mph, with gusts as high as 28 mph.
Tuesday
 
 Mostly cloudy, then gradually becoming sunny, with a high near 71. West northwest wind 8 to 17 mph, with gusts as high as 28 mph.
Tuesday Night
 
 Partly cloudy, with a low around 46. West northwest wind 5 to 7 mph becoming calm in the evening.
Wednesday
 
 Showers and thunderstorms likely, mainly before 4pm. Increasing clouds, with a high near 73. Light and variable wind. Chance of precipitation is 60%.
Wednesday Night
 
 A chance of showers and thunderstorms. Mostly cloudy, with a low around 46. Light and variable wind. Chance of precipitation is 50%.
Thursday
 
 A 30 percent chance of showers and thunderstorms after noon. Mostly sunny, with a high near 76. Calm wind becoming west around 5 mph in the afternoon.
Thursday Night
 
 A slight chance of showers and thunderstorms before 9pm, then a slight chance of showers between 9pm and midnight. Partly cloudy, with a low around 48. Light and variable wind. Chance of precipitation is 20%.
Friday
 
 Showers likely and possibly a thunderstorm after noon. Partly sunny, with a high near 76. Light and variable wind.
Friday Night
 
 A chance of showers and thunderstorms before midnight. Mostly cloudy, with a low around 47.
Independence Day
 
 Sunny, with a high near 77.
Saturday Night
 
 Mostly clear, with a low around 49.
Sunday
 
 Sunny, with a high near 85.
Sunday Night
 
 Mostly clear, with a low around 53.
Monday
 
 Sunny, with a high near 85.

 

Forecast from NOAA-NWS for Lewistown MT.