Scorching temperatures are expected to grip southeast and central Idaho through Monday, with some lower-elevation areas potentially reaching triple digits as an upper atmospheric ridge continues to suppress typical monsoon moisture patterns.
Sunday’s high temperatures are forecast near 93 degrees, with Monday climbing slightly to around 94 degrees. However, the most concerning aspect of the forecast involves lower-elevation valleys and basins, where thermometers could reach 100 degrees or higher on both days. The absence of cloud cover and light winds will allow the sun’s heat to accumulate throughout the afternoon and early evening hours.
Dry Pattern Limits Storm Development
The upper ridge axis currently positioned over the region is preventing monsoon moisture from flowing into southeast Idaho with sufficient strength to generate scattered showers and thunderstorms. This drying effect means Sunday and Monday will be predominantly sunny with minimal cloud development—conditions that will only intensify surface heating and amplify the heat stress on residents and livestock.
Wind conditions will remain light throughout the weekend and into early week. Saturday night will feature mostly clear skies with a low around 57 degrees and south winds around 6 mph, becoming light and variable after midnight. Sunday will remain sunny with light and variable winds becoming southwest 5 to 8 mph in the afternoon. Sunday night will be mostly clear with lows near 58 degrees and north-northwest winds of 5 to 7 mph shifting to east-northeast in the evening. Monday will continue mostly sunny with north-northeast winds around 6 mph, and Monday night will bring partly cloudy conditions with lows near 61 degrees.
These light winds provide little opportunity for heat relief through natural ventilation, and overnight lows remaining in the upper 50s to low 60s mean minimal cooling between days. The pattern allows heat to persist in buildings, vehicles, and outdoor environments without the moderating influence that stronger wind patterns would typically provide.
Moisture Return and Thunderstorm Potential
Relief appears likely beginning Tuesday when monsoon moisture is forecast to return to the region. The National Weather Service is calling for a 20 percent chance of showers and thunderstorms after noon Tuesday, with highs near 92 degrees. That probability increases Tuesday night, when there is a 40 percent chance of precipitation before midnight, followed by a chance of rain after midnight.
Any storms that develop Tuesday could be stronger than typical summer convection, with the potential for gusty winds, locally heavy rainfall, and small hail. Residents should remain alert for rapidly changing conditions and the possibility of flash flooding, particularly in burn scar areas where ground saturation occurs more quickly and runoff concentrates more rapidly.
The arrival of moisture and atmospheric instability may also trigger renewed convective activity from Thursday into Saturday, though conditions are expected to become drier overall during that period. Temperatures are forecast to remain near or slightly above normal during the latter part of next week.
What Comes Next
Residents are advised to take precautions during the hot spell, including staying hydrated, limiting outdoor exertion during peak heat hours, and checking on vulnerable family members and neighbors. Heat-related stress can also increase fire danger, particularly with dry vegetation and low humidity levels. Vehicles should not be left in direct sunlight with windows closed, and pets should have access to shade and fresh water.
Those in lower-elevation areas where 100-degree temperatures are possible should prepare for extended cooling needs and ensure air conditioning systems are functioning properly. Once monsoon moisture returns Tuesday, conditions are expected to moderate, though summer heat will remain a factor through the remainder of July. The transition period may bring brief periods of heavy rainfall and thunderstorm activity, so monitoring local weather updates remains important for Bonneville County residents and those throughout the region.