MONTANA — A dangerous combination of extreme heat and high moisture will impact the region through midweek, bringing continued heat stress in southeast Montana and an increasing threat of heavy rainfall, flash flooding, and locally strong thunderstorms. Unsettled weather persists into the weekend with daily storm chances and above-normal moisture.
MONDAY NIGHT
Extreme heat continues across southeast Montana, with overnight temperatures remaining unusually warm and providing little relief from recent hot conditions. Heat warnings remain in effect across much of southern and southeastern Montana, with the hottest conditions focused east of Billings.
Meanwhile, increasing moisture and an approaching disturbance will trigger showers and thunderstorms over the mountains and foothills west of Billings during the evening. Storms will spread east into central and northern portions of the area overnight. Heavy rainfall will be the primary concern, with localized rainfall rates exceeding one inch per hour. A few storms may also produce wind gusts up to 65 mph and isolated quarter-size hail. Flash flooding will be possible, especially from Livingston to Billings and northward, where a Flash Flood Watch remains in effect through early Wednesday morning.
TUESDAY
Very warm to hot conditions continue, with highs ranging from the upper 80s to around 100 degrees, warmest across eastern zones. While heat remains a significant concern, attention increasingly shifts toward abundant moisture and the potential for heavy rainfall.
Showers and thunderstorms redevelop. Storms will be capable of producing locally heavy rainfall, and saturated areas could experience runoff issues or flash flooding. Breezy north to northwest winds may develop behind overnight storms.
WEDNESDAY
The forecast remains focused on heavy rainfall potential as another round of slow-moving showers and thunderstorms develops during the afternoon and evening. Although the severe weather threat appears lower than Tuesday, the risk of excessive rainfall increases due to deep moisture and slow storm motions.
A Flash Flood Watch is in effect from noon Wednesday through early Thursday morning from Sheridan County westward through much of south-central Montana. Rainfall rates over one inch per hour remain possible, creating a heightened threat for flash flooding, especially in low-lying areas, burn scars, and locations that receive repeated rounds of rain.
Heat warnings continue across far southeastern Montana through Wednesday evening, though temperatures elsewhere trend slightly cooler.
THURSDAY
An unusually moist air mass remains in place, supporting another round of afternoon and evening showers and thunderstorms. While widespread severe weather is not expected, any stronger storm will be capable of heavy rainfall and localized flooding concerns. Temperatures generally remain seasonably warm, with highs in the 80s to lower 90s.
FRIDAY
The overall pattern changes little as moisture remains entrenched across the region. We will continue to see scattered afternoon and evening showers and thunderstorms, with locally heavy downpours possible. Temperatures remain warm but below recent peak heat levels.
SATURDAY THROUGH MONDAY
Unsettled conditions continue through the weekend and into early next week. Daily chances for afternoon and evening showers and thunderstorms persist, especially from Billings to the west. While widespread flooding is not anticipated, any storm will be capable of producing brief heavy rainfall due to exceptionally high moisture levels.
Temperatures generally hold in the 80s and 90s, bringing an end to the most extreme heat while maintaining warm summer conditions across the area.
