Harriman State Park, ID

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Henry's Fork River from Last Chance, Island Park, Idaho
Henry's Fork River from Last Chance, Island Park, Idaho - Z3lvs, CC0, via Wikimedia Commons

Today’s Forecast:

🌤
73°F
High: 73° | Low: 37°
Current Temperature
Station: IPFI1
Observed at: 1:54 pm CDT on 9/25/26
Wind: 7 mph | Humidity: 24%
This Afternoon:Sunny. High near 71, with temperatures falling to around 69 in the afternoon. Southwest wind 8 to 12 mph, with gusts as high as 25 mph.
Tonight:Partly cloudy. Low around 37, with temperatures rising to around 39 overnight. South southwest wind 2 to 9 mph, with gusts as high as 23 mph.
Saturday:Mostly sunny, with a high near 60. South southwest wind 1 to 10 mph, with gusts as high as 24 mph.
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Today’s Report:

🥾 Hiking

Excellent
  100 /100

Excellent for hiking. High near 70°F. Low rain risk (1%). Light wind (12 mph).

  • Temp: Favorable conditions
  • Rain: Favorable conditions
  • Wind: Favorable conditions
  • Thunderstorm: Favorable conditions
Tomorrow's Outlook:
Excellent 100/100
Excellent for hiking. High near 60°F. Low rain risk (2%). Light wind (10 mph).

⛺ Camping

Excellent
  100 /100

Excellent for camping. High near 70°F. Low rain risk (1%). Light wind (12 mph).

  • Temp: Favorable conditions
  • Rain: Favorable conditions
  • Wind: Favorable conditions
  • Thunderstorm: Favorable conditions
Tomorrow's Outlook:
Excellent 100/100
Excellent for camping. High near 60°F. Low rain risk (2%). Light wind (10 mph).

🛶 Paddling

Use Caution
  47 /100

Use Caution for paddling. High near 70°F. Low rain risk (1%). Breezy winds (12 mph).

  • Temp: Favorable conditions
  • Rain: Favorable conditions
  • Wind: Marginal weather factor
  • Thunderstorm: Favorable conditions
Tomorrow's Outlook:
Good 76/100
Good for paddling. High near 60°F. Low rain risk (2%). Breezy winds (10 mph).

About Harriman State Park

Harriman State Park is an Idaho destination for a premium Nordic state park with trails, river access, and year-round lodging.

Make the Most of a Harriman State Park Day

Match the route, launch, facility, or turnaround time to wind, precipitation, temperature, smoke, water, snow, road access, and daylight. Keep a shorter or more sheltered backup ready.

Weather Tips for Harriman State Park

  • Check official access notices, alerts, road or trail conditions, fire restrictions, and local forecasts before leaving.
  • Check river flow, reservoir wind, cold-water conditions, waves, lightning, and verified local ice reports before water plans; no forecast alone proves that ice is safe.
  • Carry layers, water, navigation, sun protection, and seasonal traction or flotation appropriate to the activity.
  • Allow extra time for remote roads, mountain passes, wildfire smoke, spring runoff, and limited winter daylight.

Nearby Towns and Areas

This page can also be useful when planning outdoor time near:

  • Island Park
  • Railroad Ranch
  • Last Chance
  • Mesa Falls
  • Big Springs

Plan Around the Conditions

Choose the safest version of a Harriman State Park day by matching the activity to current wind, precipitation, temperature, smoke, water or snow conditions, access, and daylight.

7-Day Forecast for Harriman State Park

🌤
73°F
High: 73° | Low: 37°
Current Temperature
Station: IPFI1
Observed at: 1:54 pm CDT on 9/25/26
Wind: 7 mph | Humidity: 24%
Fri ☀
71° 37°
0%
Sat ⛅
60° 39°
2%
Sun ☁
66° 39°
1%
Mon ⛈
63° 34°
29%
Tue ☀
62° 34°
1%
Wed ☀
62° 34°
1%
Thu ☀
63° 35°
1%

7-Day High Temperature Trend

71° Fri 60° Sat 66° Sun 63° Mon 62° Tue 62° Wed 63° Thu

7-Day Low Temperature Trend

37° Fri 39° Sat 39° Sun 34° Mon 34° Tue 34° Wed 35° Thu

📊 7-Day Outdoor Outlook

Good Fair Poor 100 Fri 100 Sat 100 Sun 65 Mon 100 Tue 100 Wed 100 Thu
Forecast data from the National Weather Service  |  Last Updated: September 25, 2026 4:17 pm CDT

Weather by Season

Winter

Winter at Harriman State Park can bring snow, ice, wind, short daylight, and rapidly changing road or trail access. Confirm grooming, avalanche information, ice conditions, and facility operations for the listed winter activities.

Spring

Spring brings freeze-thaw mud, snowmelt, high rivers, cold water, and lingering mountain snow. Lower routes usually open well before high passes and backcountry trailheads.

Summer

Summer usually offers the broadest access, but dry heat, thunderstorms, lightning, wildfire smoke, fire restrictions, reservoir wind, and cold mountain water can alter plans.

Fall

Fall brings cooler air, shorter daylight, hunting-season awareness, and early snow at elevation. Confirm seasonal services and allow extra travel time on remote roads.

Key Climate Data Points

  • Annual average temperature: around 35–42°F, using the relevant local and elevation context.
  • Annual snowfall: commonly 80–150 inches, with a long snow season.
  • Warmest months: July and August are normally warmest.
  • Coolest months: December and January are typically coolest.
  • Wettest season: winter and spring usually provide the greatest mountain precipitation, with local variation.
  • Driest season: midsummer is generally driest, despite isolated thunderstorms.
  • Best outdoor window: June through October for warm-season access, with midwinter best at established winter destinations.