FPUS65 KTFX 182200 SFPMT State Forecast For Montana National Weather Service Great Falls MT 400 PM MDT Mon May 18 2026 MTZ001>007-043-191000- West of the Continental Divide- National Weather Service Missoula MT 400 PM MDT Mon May 18 2026 ...FROST ADVISORY IN EFFECT FROM MIDNIGHT TONIGHT TO 9 AM MDT TUESDAY for Flathead/Mission Valleys...Lower Clark Fork Region...Missoula/Bitterroot Valleys...Bitterroot/Sapphire Mountains... .TONIGHT...Partly cloudy with a slight chance of rain. Widespread frost. Lows in the mid 20s to lower 30s. .TUESDAY...Partly cloudy with a chance of rain showers and a slight chance of thunderstorms. Areas of frost. Highs in the 60s. .TUESDAY NIGHT...Partly cloudy. Lows in the 30s. .WEDNESDAY...Mostly cloudy. A chance of rain in the morning, then rain showers likely in the afternoon and evening. Highs in the 60s. .THURSDAY...Partly cloudy with a chance of rain. Lows in the 30s. Highs in the 60s. .FRIDAY...Partly cloudy. Lows in the 30s to lower 40s. Highs in the upper 60s to mid 70s. .SATURDAY...Partly cloudy. Lows in the mid 30s to lower 40s. Highs in the 70s. $$ MTZ301>314-316>318-191000- Central Montana- National Weather Service Great Falls MT 400 PM MDT Mon May 18 2026 .TONIGHT...Partly cloudy. Lows 25 to 30. .TUESDAY...Increasing clouds. Slight chance of thunderstorms in the afternoon. Highs 60 to 65...45 to 55 in the mountains. .TUESDAY NIGHT...Mostly cloudy. Slight chance of rain showers. Lows 35 to 40. .WEDNESDAY...Mostly cloudy. Rain showers and slight chance of thunderstorms. Highs 50 to 60. .THURSDAY...Partly cloudy. Chance of rain. Lows 35 to 40. Highs 55 to 65. .FRIDAY...Partly cloudy. Lows 35 to 40. Highs 60 to 70. .SATURDAY...Partly cloudy. Lows 40 to 45. Highs 70 to 80. $$ MTZ315-319>330-191000- Southwest Montana- National Weather Service Great Falls MT 400 PM MDT Mon May 18 2026 .TONIGHT...Mostly clear. Lows 20 to 30...15 to 25 in the mountains. .TUESDAY...Partly cloudy. Highs 55 to 60...45 to 55 in the mountains. .TUESDAY NIGHT...Mostly cloudy in the evening then becoming partly cloudy. Slight chance of rain and snow showers. Lows 30 to 40...25 to 35 in the mountains. .WEDNESDAY...Mostly cloudy. Rain showers and slight chance of thunderstorms. Highs 45 to 55. .THURSDAY...Rain and snow likely. Lows 30 to 35. Highs 50 to 60. .FRIDAY...Partly cloudy. Lows 30 to 35. Highs 55 to 65. .SATURDAY...Partly cloudy. Lows 35 to 40. Highs 65 to 75. $$ MTZ016>027-059>062-191000- Northeast Montana- National Weather Service Glasgow MT 400 PM MDT Mon May 18 2026 .REST OF TODAY...Mostly cloudy. Highs in the mid to upper 40s. .TONIGHT...Partly cloudy. Lows in the mid to upper 20s. .TUESDAY...Sunny in the morning then becoming partly cloudy. Highs in the lower to mid 60s. .WEDNESDAY...Mostly cloudy with a chance of rain showers and a slight chance of thunderstorms. Highs near 70. Lows near 40. .THURSDAY...Mostly cloudy with a chance of rain showers. Highs in the lower to mid 60s. Lows near 40. .FRIDAY...Partly cloudy. Highs in the mid 60s to lower 70s. Lows near 40. $$ MTZ028>042-056>058-063>068-191000- South Central and Southeast Montana- National Weather Service Billings MT 400 PM MDT Mon May 18 2026 .TONIGHT...Mostly clear. Lows in the lower 20s to the lower 30s. .TUESDAY...Sunny. Highs in the upper 50s to the upper 60s. .TUESDAY NIGHT...Partly cloudy. Lows in the lower 30s to the lower 40s. .WEDNESDAY...Mostly sunny. Chance of rain showers. Highs in the mid 60s to lower 70s. .WEDNESDAY NIGHT...Showers and slight chance of thunderstorms west...and chance of showers east. Lows in the mid 30s to the mid 40s. .THURSDAY...Mostly cloudy. Showers, snow showers likely and slight chance of thunderstorms west...and chance of showers and slight chance of thunderstorms east. Highs in the mid 50s to the mid 60s. .THURSDAY NIGHT...Mostly cloudy. Slight chance of rain showers. Lows in the lower 30s to the lower 40s. .FRIDAY...Mostly sunny. Slight chance of rain showers. Highs in the lower 60s to the lower 70s. .FRIDAY NIGHT...Partly cloudy. Lows in the mid 30s to the mid 40s. .SATURDAY...Sunny. Highs in the lower 70s to the lower 80s. $$