Boise to see first triple-digit temperatures of 2026. How long will the 100s last?
Already melting in the warm weather? Boise is about to get even hotter.
High temperatures in Idaho’s capital city are expected to hit triple digits for the first time in 2026, likely on Friday.
“High pressure continues to build across the Great Basin through the weekend (bringing) hot and dry conditions,” The National Weather Service said in its most recent Idaho state forecast discussion. “The warmest days look to be Saturday with the ridge just east of Idaho.”
Forecasters say the extreme heat will be followed by “monsoonal moisture” next week.
“This will continue through the end of the week (increasing) the threat for thunderstorms each afternoon and evening,” the weather service said in its state forecast.
How long will heat wave last?
Sweltering summer heat will continue for the next few days.
According to the National Weather Service’s current forecast for Boise, high temperatures will remain in the low 100s or high 90s through early next week.
What’s the forecast like for Boise?
The Boise area was forecast to see a high temperature of 95 degrees on Thursday, July 9, with the low temperature cooling to 61 degrees overnight.
Gentle breezes were expected to blow through Boise beginning on Thursday, with light winds reaching up to 9 mph and persisting through the weekend.
“Summer heat will continue, with (the) hottest temperatures expected Friday and Saturday,” The National Weather Service office in Boise said in a Thursday post on X. “Stay cool and hydrated! Check on children, elderly and pets.”
The high for Friday is expected to hit 101, with a low of 67.
The high could hit a sweaty 102 on Saturday, the day of the Twilight Criterium race. A Kids Ride and Junior Race are panned as well.
If you’re attending, come prepared to face extreme heat and blistering sun in downtown Boise.
The overnight low will hit 67 degrees on Saturday as winds calm.
High temperatures are expected to hover near 99 degrees Sunday through Wednesday, while lows will be in the mid- to high 60s.
How to avoid heat illness
When temperatures are extremely high, some people’s bodies can have trouble regulating temperature.
In some cases, people can experience heat exhaustion and have muscle cramps, nausea, weakness and cold or clammy skin, according to the Centers for Disease Control and Prevention.
If heat exhaustion persists for too long, however, it can lead to heatstroke, the most serious form of heat injury.
People experiencing heatstroke can have hot, red, dry or damp skin. They also can have a fast and strong pulse, and they can become confused.
If you start experiencing symptoms, move indoors immediately and call 911 right away.
If you choose to hike or be outdoors in dangerously hot temperatures, the National Park Service recommends following these safety tips:
- Carry and drink plenty of water and plan to replenish electrolytes.
- Eat twice as much food as normal and have salty foods on hand.
- Carry a first-aid kit.
- Pack essentials only.
- Bring a flashlight with spare batteries to hike during the cool evening.
- Spray yourself with water to cool down.
- Have a hat and sunscreen as protection from the sun.
- Have a whistle or signal for emergency use.
- Wear waterproof clothing if needed.
This story was originally published July 9, 2026 at 10:56 AM.
