FNUS55 KMSO 180740 FWFMSO Fire Weather Planning Forecast for Wrn Montana and N Cntrl Idaho National Weather Service Missoula MT 140 AM MDT Mon May 18 2026 .DISCUSSION... Idaho (Zones 102 and 103): Cold mornings through Tuesday with an unstable atmosphere producing isolated showers. Expect a warming trend through the end of week, with the potential for weak disturbances. Northwest MT (Zones 104 and 105): Cold mornings through Tuesday with an unstable atmosphere producing isolated showers. Expect a warming trend through the end of week, with the potential for weak disturbances. West Central MT (Zones 106, 107 and 108): Cold mornings through Tuesday with an unstable atmosphere producing isolated showers. Expect a warming trend through the end of week, with the potential for weak disturbances. Southwest MT (Zones 109, 110 and 111): Cold mornings through Tuesday with an unstable atmosphere producing isolated showers. Expect a warming trend through the end of week, with the potential for weak disturbances. IDZ102-103-190745- Palouse/Hells Canyon-Clearwater/Nez Perce- 1240 AM PDT Mon May 18 2026 .TODAY... * Sky/Weather.........Partly cloudy. Widespread frost in the morning. Slight chance of thunderstorms in the afternoon. Snow level 5500 feet. * Max Temperature.....60-70 valleys and 45-55 ridges. * Min Humidity........38-48 percent. * 20-Foot Winds....... * Lower Elevation......Calm to becoming upslope/upvalley 4-8 mph in the afternoon. * Ridge Top............North 5-15 mph. * Mixing Height.......Below 500 ft to 1 kft agl until 0900. 7 kft agl after 1300. * Transport Winds.....Variable less than 10 mph until 1000, then north 10 mph. * Chance Lightning....20 percent. * CWR (> 0.10 Inch)...10 percent. .TONIGHT... * Sky/Weather.........Partly cloudy. Slight chance of rain. Widespread frost after midnight. Snow level 6500 feet. * Min Temperature.....35-40 valleys and 28-38 ridges. * Max Humidity........67-77 percent. * 20-Foot Winds....... * Lower Elevation......Northwest 5-10 mph in the evening becoming downslope/downvalley 2-5 mph. * Ridge Top............West 5-15 mph. * Mixing Height.......5 kft agl until 2000. Below 500 ft to 1 kft agl after 2200. * Transport Winds.....Northwest 10 mph until 2300, then variable less than 10 mph. * Chance Lightning....Near 0 percent. * CWR (> 0.10 Inch)...0 percent. .TUESDAY... * Sky/Weather.........Partly cloudy. Widespread frost in the morning. * Max Temperature.....63-73 valleys and 50-60 ridges. * Min Humidity........28-38 percent valleys and 35-45 percent ridges. * 20-Foot Winds....... * Lower Elevation......Calm to becoming upslope/upvalley 4-8 mph in the afternoon. * Ridge Top............West 5-15 mph. * Mixing Height.......Below 500 ft to 1 kft agl until 0900. 9 kft agl after 1600. * Transport Winds.....Variable less than 10 mph until 1000, then west 10 mph. * Chance Lightning....Near 0 percent. * CWR (> 0.10 Inch)...0 percent. .WEDNESDAY...Partly cloudy. Lows 40-50. Highs 60-70. Min humidities 25-35 percent. West winds 5-10 mph. .THURSDAY...Partly cloudy. Lows 40-50. Highs 65-75. Min humidities 20-30 percent. North winds 10-15 mph. .FRIDAY...Partly cloudy. Lows 40-50. Highs 65-75. West winds 5-10 mph. .SATURDAY...Partly cloudy. Lows 45-55. Highs 70-80. .SUNDAY...Partly cloudy. Lows 45-55. Highs 70-80. $$ MTZ104-105-190745- Kootenai-Flathead/Glacier Park- 140 AM MDT Mon May 18 2026 .TODAY... * Sky/Weather.........Partly cloudy. Widespread frost in the morning. Chance of snow showers and slight chance of thunderstorms in the afternoon. Snow level 5000 feet. * Max Temperature.....60-65 valleys and 43-53 ridges. * Min Humidity........32-42 percent valleys and 50-60 percent ridges. * 20-Foot Winds....... * Lower Elevation......Calm to becoming upslope/upvalley 4-8 mph in the afternoon. * Ridge Top............Northwest 5-15 mph. * Mixing Height.......Below 500 ft to 1 kft agl until 0900. 7 kft agl after 1100. * Transport Winds.....Northwest 10 mph until 1500, then west 10 mph. * Chance Lightning....25 percent. * CWR (> 0.10 Inch)...10 percent. .TONIGHT... * Sky/Weather.........Partly cloudy. Slight chance of rain and snow. Widespread frost after midnight. Snow level 6000 feet. * Min Temperature.....28-38. * Max Humidity........93-100 percent valleys and 81-91 percent ridges. * 20-Foot Winds....... * Lower Elevation......Downslope/downvalley 2-5 mph. * Ridge Top............Southwest 5-15 mph. * Mixing Height.......4 kft agl until 2000. Below 500 ft to 1 kft agl after 2200. * Transport Winds.....Southwest 10 mph. * Chance Lightning....Near 0 percent. * CWR (> 0.10 Inch)...10 percent. .TUESDAY... * Sky/Weather.........Partly cloudy. Widespread frost in the morning. Slight chance of thunderstorms in the afternoon. Snow level 6500 feet. * Max Temperature.....60-70 valleys and 45-55 ridges. * Min Humidity........36-46 percent valleys and 53-63 percent ridges. * 20-Foot Winds....... * Lower Elevation......Calm to becoming upslope/upvalley 4-8 mph in the afternoon. * Ridge Top............West 10-20 mph. * Mixing Height.......1-2 kft agl until 0900. 8 kft agl after 1100. * Transport Winds.....West 15 mph. * Chance Lightning....20 percent. * CWR (> 0.10 Inch)...10 percent. .WEDNESDAY...Partly cloudy with rain showers likely and slight chance of thunderstorms. Chance of precipitation 60 percent. Lows 35-45. Highs 55-65. Min humidities 30-40 percent. Southwest winds 10-20 mph. .THURSDAY...Partly cloudy with chance of rain. Chance of rain 50 percent. Lows 35-45. Highs 60-70. Min humidities 25-35 percent. Northwest winds 10-15 mph. .FRIDAY...Partly cloudy with slight chance of rain. Chance of rain 20 percent. Lows 40-50. Highs 60-70. Southwest winds 10-15 mph. .SATURDAY...Partly cloudy. Lows 40-50. Highs 65-75. .SUNDAY...Partly cloudy. Lows 40-50. Highs 65-75. $$ MTZ106-108-190745- West Lolo-East Lolo- 140 AM MDT Mon May 18 2026 .TODAY... * Sky/Weather.........Partly cloudy. Widespread frost in the morning. Slight chance of thunderstorms and snow in the afternoon. Snow level 5000 feet. * Max Temperature.....55-65 valleys and 45-55 ridges. * Min Humidity........33-43 percent valleys and 40-50 percent ridges. * 20-Foot Winds....... * Lower Elevation......Calm to variable less than 7 mph. * Ridge Top............Northwest 5-10 mph. * Mixing Height.......1-2 kft agl until 0900. 8 kft agl after 1400. * Transport Winds.....North 10 mph. * Chance Lightning....20 percent. * CWR (> 0.10 Inch)...10 percent. .TONIGHT... * Sky/Weather.........Partly cloudy. Slight chance of rain. Widespread frost after midnight. Snow level 6000 feet. * Min Temperature.....25-35. * Max Humidity........85-95 percent valleys and 75-85 percent ridges. * 20-Foot Winds....... * Lower Elevation......Downslope/downvalley 2-5 mph. * Ridge Top............West 5-15 mph. * Mixing Height.......6 kft agl until 1900. Below 500 ft to 1 kft agl after 2200. * Transport Winds.....West 10 mph until 0500, then southwest 10 mph. * Chance Lightning....Near 0 percent. * CWR (> 0.10 Inch)...10 percent. .TUESDAY... * Sky/Weather.........Partly cloudy. Widespread frost in the morning. * Max Temperature.....53-63. * Min Humidity........27-37 percent valleys and 43-53 percent ridges. * 20-Foot Winds....... * Lower Elevation......West 5-15 mph. * Ridge Top............Southwest 5-10 mph becoming west 10-20 mph in the afternoon. * Mixing Height.......1-2 kft agl until 0900. 9 kft agl after 1400. * Transport Winds.....West 10 mph until 1100, then 15 mph. * Chance Lightning....20 percent over the West Lolo...and near 0 percent toward the East Lolo. * CWR (> 0.10 Inch)...0 percent. .WEDNESDAY...Partly cloudy. Lows 35-45. Highs 55-65. Min humidities 35-45 percent. West winds 10-15 mph. .THURSDAY...Partly cloudy with chance of rain. Chance of rain 50 percent. Lows 35-45. Highs 60-70. Min humidities 20-30 percent. Northwest winds 10-15 mph. .FRIDAY...Partly cloudy. Lows 40-50. Highs 65-75. West winds 5-10 mph. .SATURDAY...Partly cloudy. Lows 40-50. Highs 65-75. .SUNDAY...Partly cloudy. Lows 45-55. Highs 65-75. $$ MTZ107-190745- Flathead Reservation- 140 AM MDT Mon May 18 2026 .TODAY... * Sky/Weather.........Partly cloudy. Widespread frost in the morning. Slight chance of thunderstorms in the afternoon. Snow level 5000 feet. * Max Temperature.....60-65 valleys and 40-45 ridges. * Min Humidity........34-44 percent. * 20-Foot Winds....... * Lower Elevation......Calm to becoming upslope/upvalley 4-8 mph in the afternoon. * Ridge Top............Northwest 5-15 mph. * Mixing Height.......Below 500 ft to 1 kft agl until 0900. 7 kft agl after 1300. * Transport Winds.....Variable less than 10 mph until 1400, then northwest 10 mph. * Chance Lightning....20 percent. * CWR (> 0.10 Inch)...10 percent. .TONIGHT... * Sky/Weather.........Partly cloudy. Slight chance of rain. Areas of frost after midnight. Snow level 6000 feet. * Min Temperature.....30-40. * Max Humidity........69-79 percent. * 20-Foot Winds....... * Lower Elevation......Downslope/downvalley 2-5 mph. * Ridge Top............Southwest 5-10 mph. * Mixing Height.......4 kft agl until 2000, then below 500 ft to 1 kft agl. * Transport Winds.....West 10 mph until 2300, then variable less than 10 mph. * Chance Lightning....Near 0 percent. * CWR (> 0.10 Inch)...10 percent. .TUESDAY... * Sky/Weather.........Partly cloudy. Slight chance of thunderstorms in the afternoon. Snow level 7000 feet. * Max Temperature.....65-70 valleys and 45-50 ridges. * Min Humidity........36-46 percent valleys and 48-58 percent ridges. * 20-Foot Winds....... * Lower Elevation......Southwest 5-15 mph. * Ridge Top............Southwest 5-15 mph becoming west 10-20 mph in the afternoon. * Mixing Height.......Below 500 ft to 1 kft agl until 0900. 8 kft agl after 1100. * Transport Winds.....Southwest 10 mph until 1200, then west 15 mph. * Chance Lightning....20 percent. * CWR (> 0.10 Inch)...10 percent. .WEDNESDAY...Partly cloudy. Lows 40-50. Highs 60-70. Min humidities 35-45 percent. Southwest winds 10-15 mph. .THURSDAY...Partly cloudy with chance of rain. Chance of rain 50 percent. Lows 40-50. Highs 60-70. Min humidities 25-35 percent. Northwest winds 10-15 mph. .FRIDAY...Partly cloudy. Lows 45-55. Highs 65-75. Southwest winds 5-10 mph. .SATURDAY...Partly cloudy. Lows 45-55. Highs 70-80. .SUNDAY...Partly cloudy. Lows 45-55. Highs 70-80. $$ MTZ109-190745- Bitterroot- 140 AM MDT Mon May 18 2026 .TODAY... * Sky/Weather.........Partly cloudy. Widespread frost in the morning. Slight chance of thunderstorms and snow in the afternoon. Snow level 5000 feet. * Max Temperature.....60-65 valleys and 40-45 ridges. * Min Humidity........22-32 percent valleys and 38-48 percent ridges. * 20-Foot Winds....... * Lower Elevation......Calm to variable less than 7 mph. * Ridge Top............North 5-15 mph. * Mixing Height.......Below 500 ft to 1 kft agl until 0800. 8 kft agl after 1500. * Transport Winds.....North 10 mph until 1200, then 15 mph. * Chance Lightning....20 percent. * CWR (> 0.10 Inch)...10 percent. .TONIGHT... * Sky/Weather.........Partly cloudy. Slight chance of rain and snow. Widespread frost after midnight. Snow level 6000 feet. * Min Temperature.....25-35. * Max Humidity........68-78 percent. * 20-Foot Winds....... * Lower Elevation......North 5-10 mph in the evening becoming downslope/downvalley 2-5 mph. * Ridge Top............West 5-15 mph. * Mixing Height.......5 kft agl until 2000. Below 500 ft to 1 kft agl after 2400. * Transport Winds.....Northwest 10 mph until 2400, then variable less than 10 mph. * Chance Lightning....Near 0 percent. * CWR (> 0.10 Inch)...10 percent. .TUESDAY... * Sky/Weather.........Partly cloudy. * Max Temperature.....65-70 valleys and 45-50 ridges. * Min Humidity........21-31 percent valleys and 35-45 percent ridges. * 20-Foot Winds....... * Lower Elevation......Calm to becoming upslope/upvalley 4-8 mph in the afternoon. * Ridge Top............West 5-15 mph. * Mixing Height.......Below 500 ft to 1 kft agl until 0900. 9 kft agl after 1300. * Transport Winds.....West 10 mph until 1300, then 15 mph. * Chance Lightning....Near 0 percent. * CWR (> 0.10 Inch)...0 percent. .WEDNESDAY...Partly cloudy. Lows 35-45. Highs 55-65. Min humidities 25-35 percent. West winds 10-15 mph. .THURSDAY...Partly cloudy with slight chance of rain. Chance of rain 20 percent. Lows 35-45. Highs 60-70. Min humidities 15-25 percent. Northwest winds 10-20 mph. .FRIDAY...Partly cloudy. Lows 40-50. Highs 60-70. West winds 10-15 mph. .SATURDAY...Partly cloudy. Lows 40-50. Highs 65-75. .SUNDAY...Partly cloudy. Lows 40-50. Highs 70-80. $$ MTZ110-111-190745- Deerlodge/West Beaverhead-East Beaverhead- 140 AM MDT Mon May 18 2026 .TODAY... * Sky/Weather.........Partly cloudy. * Max Temperature.....45-55 valleys and 35-45 ridges. * Min Humidity........27-37 percent. * 20-Foot Winds....... * Lower Elevation......North 20-30 mph. * Ridge Top............North 25-35 mph decreasing to 15-25 mph in the afternoon. * Mixing Height.......3 kft agl until 0900. 8 kft agl after 1300. * Transport Winds.....North 20 mph. * Chance Lightning....Near 0 percent. * CWR (> 0.10 Inch)...0 percent. .TONIGHT... * Sky/Weather.........Partly cloudy. Widespread frost after midnight. * Min Temperature.....20-25. * Max Humidity........75-85 percent valleys and 63-73 percent ridges. * 20-Foot Winds....... * Lower Elevation......Northwest 10-20 mph in the evening becoming downslope/downvalley 5-10 mph. * Ridge Top............North 10-20 mph becoming west 5-10 mph after midnight. * Mixing Height.......7 kft agl until 2000. Below 500 ft to 1 kft agl after 2100. * Transport Winds.....North 15 mph until 2100, then variable less than 10 mph. * Chance Lightning....Near 0 percent. * CWR (> 0.10 Inch)...0 percent. .TUESDAY... * Sky/Weather.........Partly cloudy. Slight chance of snow in the afternoon. Snow level 6500 feet. * Max Temperature.....55-60 valleys and 45-50 ridges. * Min Humidity........23-33 percent. * 20-Foot Winds....... * Lower Elevation......West 5-15 mph. * Ridge Top............West 5-15 mph. * Mixing Height.......Below 500 ft to 1 kft agl until 0800. 11 kft agl after 1400. * Transport Winds.....West 10 mph until 1300, then 15 mph. * Chance Lightning....Near 0 percent. * CWR (> 0.10 Inch)...10 percent. .WEDNESDAY...Partly cloudy. Lows 30-40. Highs 55-65. Min humidities 25-35 percent. West winds 10-15 mph. .THURSDAY...Partly cloudy with chance of rain and snow. Chance of precipitation 30 percent. Lows 35-45. Highs 55-65. Min humidities 20-30 percent. Northwest winds 10-15 mph. .FRIDAY...Partly cloudy. Lows 35-45. Highs 60-70. West winds 10-15 mph. .SATURDAY...Partly cloudy. Lows 35-45. Highs 65-75. .SUNDAY...Partly cloudy. Lows 40-50. Highs 70-80. $$