Hells Canyon, Idaho
Hells Canyon Weather by Month: Snake River Temperatures and Best Time to Raft
Hells Canyon is the hottest river destination that Western River offers in Idaho, set on the floor of the deepest river gorge in North America. Because the Snake here is released from Hells Canyon Dam just upstream, the water stays strong and runnable all season. The best time to go depends on the experience you want.
- Choose May or June for higher dam flows, big early-season whitewater and a quieter canyon, keeping in mind cooler air and colder water (wetsuits are provided).
- Choose July or August for the hottest days, the warmest swimmable water and long afternoons on the white-sand beaches.
- Choose September for a second high-water peak, comfortable temperatures and an uncrowded end to the rafting season.
There is no single month that is best for everyone. Spring in Hells Canyon and late summer in Hells Canyon can feel like two different trips, and both run the same 79 miles of the Snake River through the deepest river gorge in North America. Below, you can compare monthly weather, Snake River water temperatures and the dam-controlled flow, and find the best time for your group.
Best Month to Raft Hells Canyon: Air Temperatures & Precip
The best time to raft Hells Canyon depends on the experience that sounds best to you: big early-season water in a quiet canyon, the hottest days and warmest swimming water of summer, or a second high-water peak with comfortable fall temperatures. Because the dam keeps the water consistent, every month delivers strong whitewater.
| MONTH | AVG HIGH / LOW (°F) | RIVER WATER | AVG MONTHLY PRECIPITATION (INCHES) | WHAT IT FEELS LIKE | WHY CHOOSE IT |
|---|---|---|---|---|---|
| MAY | 69° / 40° | ~60°F, higher dam flows | 1.42 | Cooler temperate days, quiet canyon and big early-season water | Early-season quiet and higher flows, cooler air and active wildlife (wetsuits provided) |
| JUNE | 82° / 51° | ~60°F, a high-water peak | 1.42 | Warming days against one of the season’s biggest flows | Anticipate a high-water peak from the dam release. Generally the most powerful rapids of the season. |
| JULY | 92° / 58° | ~70°F | 1.03 | Hot canyon days, warm swimmable water and long sunny afternoons | Peak heat and swimming, the most popular family window |
| AUGUST | 94° / 56° | ~70°F | 0.82 | The hottest stretch, warm water and white-sand beach time | The hottest, warmest-water weeks for swimming, fishing and beach days |
| SEPTEMBER | 82° / 47° | ~60°F, second high-water peak | 0.77 | Cooling days, crisp nights and excellent flows in a quiet canyon | Fewer crowds and comfortable temperatures |
Why Hells Canyon Water Levels Stay Strong All Season
Hells Canyon’s low elevation and limited shade make for hot summers, with July and August afternoons typically reaching the low-to-mid 90s°F.
Upstream dam releases help maintain dependable Snake River rafting flows throughout the season. Unlike rivers that rely on spring snowmelt, Hells Canyon offers whitewater all summer.
Guests can choose from three types of river craft, often trying more than one during the trip.
Oar Boat
Rowed by expert, professional guides, the oar boat is the most relaxed way through the gorge. You take in the canyon walls and hang on through the rapids while the guide does the work.
Paddle Boat
A guided paddle raft for guests who want to be in the action. Your guide steers and calls the strokes, and the crew provides the power through the Class II to IV whitewater.
Inflatable Kayak
A one or two-person inflatable kayak for the most hands-on ride. Steering and power are yours, the most direct way to feel the Snake's pool-and-drop rapids.
The Best Weather Forecast to Check
For temperatures on the canyon floor, the best nearby reference points are Lewiston or Clarkston near the river’s lower end, and Cambridge or the Hells Canyon Dam area near the put-in. These low elevation, sheltered locations are hot and provide a better indication of conditions in the gorge than nearby high elevation towns.
Use the forecast as a general guide. The trip covers about 79 miles of remote gorge, and the deep floor can run hotter than any town reading. Pack for serious heat and strong sun in summer, cooler nights in spring and fall, and rely on your guides, who watch conditions and shape each day around the group.
What Each Month Feels Like in Hells Canyon
Spring
May & June: Big Water, Fewer Crowds
Spring is the raw, dramatic Hells Canyon. The dam releases higher, colder and faster water, the whitewater is at its most powerful, and the canyon feels alive with wildflowers and active wildlife. Days are temperate, with highs climbing from around 69°F in May into the low 80s by June, and nights stay cool. The water is cold enough this early that you'll be provided full wetsuits.
Choose May or June for: The biggest water, quieter camps and a cooler canyon.
SUMMER
July & August: Hot Days, Warm Water
Midsummer is the hot, bright heart of the season. Afternoons reach the low-to-mid 90s°F on the deep canyon floor, the dam-warmed water settles around 70°F, and long days open up for swimming, fishing and lingering on the white-sand beaches. Nights stay mild, often in the upper 50s, and the stars come out over one of the deepest gorges on the continent. Sun protection is the price of admission, and the warm river is the reward.
Choose July or August for:
Warm water, peak heat and the strongest family travel window.
Fall
September: The Second High-Water Peak
September brings a second dam high-water peak, so the whitewater stays strong even as the air cools. Highs ease back toward 82°F, nights turn crisp into the 40s, the water cools toward 60°F, and the gorge feels calm and uncrowded.
Choose September for:
Excellent flows, comfortable days and a quieter canyon.
Pick Your Month to Raft Hells Canyon
Hells Canyon in May is a cold-water, big-flow, wetsuit-provided spring trip. In August it is a hot-gorge, warm-water, swim-all-day summer one. Same 79 miles, same deepest gorge in North America, with the dam keeping the water strong across the whole season.
Questions? Call (801) 459-3525 and talk to someone who has been there.
Snake River Water Temperature in Hells Canyon
Here is where Hells Canyon parts company with the Salmon rivers. The Salmon trips run on free-flowing snowmelt, while the Snake River through Hells Canyon is released from Hells Canyon Dam just upstream, so its temperature and flow are shaped by dam operations rather than the snowpack alone.
What that means in practice is that spring water runs colder off the dam, around 60°F in June, which is why you're provided full wetsuits and booties on early-season trips. As summer settles in, the river warms to around 70°F in July and August, comfortable for swimming, and most guests are in and out of the water all day. September cools it back toward 60°F. Across the season the Snake here averages around 65°F.
So the Snake River water temperature story is a dam story, not a pure-snowmelt one: colder in spring and fall, warm through midsummer. Plan your gear around the season. On May and June trips, let your provided wetsuit do the work, and keep a two-piece rain suit in your day bag for cool mornings and the occasional splash on the bigger rapids.
Warm Days, Cool Rivers
Summer days in Hells Canyon are often warm, especially in July and August, but the Snake River is never far away. Between rapids, many guests cool off with a swim, float beside the raft, or simply dangle their feet in the water during lunch stops. Mornings are comfortable, evenings are ideal for camp, and the river itself becomes the best relief from the afternoon sun.
Brief afternoon thunderstorms occasionally drift through the canyon, bringing dramatic skies and a welcome drop in temperature before clearing just as quickly. A light rain layer and good sun protection are usually all you'll need for changing conditions.
North America's Deepest Gorge
Hells Canyon plunges nearly 8,000 feet from He Devil Peak to the Snake River, making it deeper than the Grand Canyon. Those dramatic elevation changes create equally dramatic weather: cool mountain mornings can give way to hot canyon afternoons only a few miles away. Early settlers named the forbidding gorge and the neighboring Seven Devils peaks for the harsh terrain and intimidating landscape rather than any single historic event.
Adventure with confidence
Common Weather Questions
What is the best time to raft Hells Canyon?
Every month runs well, because the dam keeps the water strong all season. May and June bring higher dam flows, cooler air (days roughly 65 to 82°F), active wildlife and provided wetsuits. July and August are the hottest and most popular, with days in the low-to-mid 90s, water around 70°F and long afternoons for swimming and fishing. September brings a second high-water peak, cooler air and a quieter canyon. Families and heat-lovers lean toward July through September, while guests who want the biggest water choose May, June or September.
Is there a wrong month for whitewater in Hells Canyon?
Generally no, and that is the dam's doing. Because Hells Canyon Dam controls flow, the river holds consistent, excellent levels all season, unlike snowmelt rivers that drop as summer goes on. There are even two high-water peaks, one in June and one in September, from controlled releases. The choice here is mostly about heat and crowds, not whether the rapids will run.
When is the Hells Canyon rafting season?
Western River offers Hells Canyon May through September on the Snake River through North America's deepest gorge. Trips begin in Boise or Cambridge, Idaho and end in Lewiston, with a choice of oar boat, paddle raft or inflatable kayak.
How far in advance should I book?
Earlier than you might expect for the hot, popular July and August weeks and the excellent September shoulder. Western River offers a limited number of permitted departures each season, so popular dates fill early. Reserve as soon as your dates are set.
How hot does Hells Canyon get?
As the deepest gorge in North America, its low canyon floor heats up more than the higher Idaho canyons, and July and August afternoons reach the low-to-mid 90s°F. The deep, sheltered gorge can feel hotter still on a still day. The dry air helps and the river is always there to cool off in, but sun protection is essential because there is little shade. Nights are mild in midsummer, often in the upper 50s, and cooler in spring and fall.
How cold is the Snake River water in Hells Canyon?
It depends on the season, and the dam is the reason. Because the Snake is released from Hells Canyon Dam just upstream, spring water runs colder, around 60°F by June, cold enough that you will be provided full wetsuits and booties on those early-season trips. By July and August the water warms to around 70°F and most guests swim freely. September cools it back toward 60°F, and across the season the river averages around 65°F.
Does it get cold at night in Hells Canyon?
In midsummer, not much. July and August nights stay mild, often in the upper 50s, warm enough for stargazing in a light layer. Spring and fall are different, with May, June and September nights dropping into the 40s and low 50s, so a warm layer for camp and the morning matters on those trips. A two-piece rain suit also handles the occasional summer thundershower.
Still curious to learn more? Contact us.
Hells Canyon Reviews
"It's Not Disneyland, and That's Why You Go"
★★★★★
A great team of six guided fifteen of us down the Snake through Hells Canyon for 80-plus miles, and worked their butts off in the process. Lots of laughs. Lots of stories. Lots of rafting danger safely shared with professional guidance. It's not Disneyland. And that's why you want to go.
Steve Holcombe, Google
"The Guides Took Excellent Care of Me"
★★★★★
I was on a 5 day rafting trip on the Snake River in Idaho. The guides took excellent care of me. Given the remoteness of the canyon, this was not an easy thing. I can't say enough about our guides' empathy, professionalism and care. Looking forward to enjoying this trip on another occasion.
Kerry Fisher, Google
"The Best Company Hands Down in Idaho"
★★★★★
All guides are very good at what they do and they take it to another level with their knowledge of the river and its history. Great food, great activities and first class service. I'll never use anyone else.
Kevin, Google
★★★★★
360+ REVIEWS
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800+ REVIEWS
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1K+ REVIEWS
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Choosing Your Hells Canyon Trip
Western River offers Hells Canyon as a single 5-day expedition, 79 miles of the Snake River through the deepest gorge in North America. Whichever month you choose, the dam keeps the water strong, and you pick the craft that fits how you want to run the river: oar boat, paddle raft or inflatable kayak.
Five days on the Snake River through Hells Canyon, the deepest river gorge in North America, with powerful rapids, towering basalt walls, and rich Nez Perce history.
- Begins: Cambridge, ID
- Best for: Rapids & beaches
- Rapids: 40+ Class III-IV
- Ages: June 12+ Jul/Aug 8+
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