Thunderstorms, heavy rain headed to Boise area. Where could there be flooding?
Heavy rains are headed to Boise, putting some areas at risk for flash flooding, weather officials said.
“Moderate/heavy rainfall is possible with stronger storms,” particularly on Tuesday through Thursday, the National Weather Service in Boise said in a post on X, formerly known as Twitter. “This could lead to flash flooding on burn scars and also cause impacts to outdoor activities,” the weather service said.
Thunderstorms are expected earlier in the week, according to AccuWeather.
As of 10 a.m. Monday, southwestern Idaho had received a 10th of an inch of rain, the National Weather Service said in an update.
The coolest temperatures are expected on Wednesday, the National Weather Service said.
Here’s how often Boise could see storms this week:
What’s in the weather forecast for Boise?
Thunderstorms were expected to rumble through the Treasure Valley between Monday and Wednesday, though chances of rain continue through Thursday, according to the National Weather Service’s latest forecast.
“Moisture will continue to deepen across the region through Wednesday, bringing increasing coverage of showers and thunderstorms,” the National Weather Service said in its forecast discussion. “The primary concern will be excessive rainfall, especially on Wednesday.”
Monday will likely be the hottest day of the week for Boise with a high temperature of 90 degrees, weather officials said.
There’s a 30% chance of rain on Monday night with temperatures expected to dip as low as 66 degrees.
Tuesday will have similar temperatures with a high of 89 and a low of 66, the weather service said in its forecast, with a 10th to a quarter of an inch of new rain expected to fall.
Boise could see a “stray” thunderstorm in the afternoon, AccuWeather predicts.
Thunderstorms and “heavy” rains are expected all day Wednesday with scattered storms in the morning and isolated storms in the evening, The Weather Channel said.
Wednesday is expected to be the coolest day of the week with a high of 76 and a low of 64, the National Weather Service predicted. Boise could see between a 10th and a quarter of an inch of new rainfall.
According to the National Weather Service, there is a 40% chance of rain during the day on Thursday and a 20% chance of rain in the evening. The high will be 81 and the low will be 61.
The Boise area wasn’t expected to see rain Friday through Sunday, according to The Weather Channel.
Friday will have a high of 89 degrees and a low of 63 degrees.
Saturday will see a high of 89 degrees and a low of 63 degrees, while Sunday will have a high of 90 degrees and a low of 62 degrees.
What is the risk of flash flooding?
On Tuesday, the National Weather Service issued a flash flood watch for the Treasure Valley, AccuWeather and The Weather Channel reported.
The flash flood watch, which impacts parts of Idaho and Oregon, will be in effect from Tuesday afternoon through Wednesday evening, the weather service said.
“Heavy rainfall could trigger flash flooding or debris flows in and near recent wildfire burn scars,” the weather service said. “In addition, urban street flooding is possible with the stronger storms.”
As of Monday morning, forecasters had not predicted how many inches of rain the Boise area could get over the course of the week.
Burn scars — areas of land scorched by wildfires — are at the greatest risk for flash flooding during the storms, the National Weather Service said.
In Idaho, the Wapiti Fire burn scar near Grandjean and the Lava Fire burn scare near Cascade are of “particular concern for flash flooding,” weather officials said. So is the Durkee Fire burn scar near Ironside, Oregon.
What will the weather in Idaho be like this fall?
Idaho is expected to see mostly warm, dry weather this fall, according to the Old Farmer’s Almanac.
The average temperature in September will be 67 degrees, the Old Farmer’s Almanac said, while October is expected to have an average daily temperature of 52 degrees.
Idaho will see below-average rainfall in the fall, the almanac said in its 60-day prediction.
This story was originally published August 25, 2025 at 12:10 PM.