UV Index Today in Boise, Idaho

Current UV
Today's Max

Hourly UV Forecast

low moderate high very high extreme

Surface Type

Reflective surfaces increase your UV exposure — snow reflects up to 90%, sand about 20%.

Safe Exposure Time

Estimated burn times based on the Fitzpatrick scale for skin color and today's maximum UV index of . Tap your skin type:

Very fair skin, always burns, never tans

Time until burn
With SPF 15*
With SPF 30*

*Assumes proper application of broad-spectrum sunscreen with reapplication every 2 hours. Estimates follow WHO guidance and satellite-derived data — see how our data works.

Sun Times

Dawn
Sunrise
Solar Noon
Sunset
Dusk
Day Length
Morning Golden Hour Ends
Evening Golden Hour

Important Safety Information

General Guidelines

These exposure times are estimates based on scientific research and should be used as general guidelines only. Individual responses to UV exposure may vary.

Affecting Factors

UV exposure is affected by: time of day, season, altitude, cloud cover, reflection from surfaces, and individual skin sensitivity.

Protection Tips

Seek shade during peak UV hours (10 AM - 4 PM), wear protective clothing, use broad-spectrum sunscreen, and monitor the UV index regularly.

Medical Advice

Consult a healthcare provider for personalized sun protection advice, especially if you have a history of skin conditions or take medications that increase sun sensitivity.

Boise's UV Climate

Boise sits at 2,700 feet where the high desert meets the Rocky Mountain foothills, and its combination of altitude, dry air, and abundant sunshine produces stronger UV than its northern latitude suggests. The city lives outdoors — floating the Boise River through downtown is a summer institution, and the foothills trail system climbs quickly into even thinner air — so peak-season exposure is both intense and prolonged, often on reflective water.

Average Annual UV Index

6.3

Peak UV Season

May - September

Sunny Days per Year

206

Typical UV Index by Season in Boise

Season Typical Midday UV Protection Needed
Summer Very High (8-10) SPF 30+, hat, sunglasses; shade from 10 AM – 4 PM
Spring & Fall Moderate to High (4-7) SPF 30+ for extended time outdoors
Winter Low (1-3) Sunscreen for long midday exposure; more on snow

UV Index in Nearby Cities

Practical Tips for Outdoor Activities

Make the most of outdoor activities while staying safe in Ada County:

UV and Weather in Ada County

Learn about Ada County's unique climate patterns, UV radiation levels, and how they affect your daily life. Enter your zip code for location-specific weather radar data and UV forecasts to help you make informed decisions about outdoor activities and sun protection.

Climate and UV Patterns

Boise's semi-arid climate delivers hot, dry, exceptionally clear summers with midday UV index values of 8-10, elevated roughly 10-15% by altitude. Humidity is minimal, so there's rarely haze to scatter UV, and cloudless stretches can run for weeks in July and August. Winters are cold and often overcast in the valley, though inversion-topping foothill hikes and nearby Bogus Basin skiing find clearer, stronger sun.

UV Index and Health Impact

Understanding UV radiation levels is crucial for protecting your health. Typical clear-day UV index values in Boise through the year:

  • Summer: Very High (8-10)
  • Spring/Fall: Moderate to High (4-7)
  • Winter: Low (1-3)
  • Peak UV hours: 10 AM - 4 PM
  • Cloud cover can reduce UV by 20-40%, but does not eliminate it
  • Clear skies bring maximum UV exposure

Local Weather Patterns

Summer in Boise means day after day of deep-blue sky, with river floaters getting a double dose from direct sun and water reflection during two-plus-hour trips through minimal shade. Late summer wildfire smoke sometimes dims the sun for stretches. Winter valley inversions trap gray cloud over the city while the mountains above sit in bright sunshine — skiers gain both altitude UV and snow reflection on those days.

Frequently Asked Questions About UV in Boise

What is the UV index in Boise today?

The live UV index for Boise, ID is shown at the top of this page and updates throughout the day, along with today's maximum and an hourly forecast.

When is the sun strongest in Boise?

UV radiation is strongest between 10 AM and 4 PM. Boise's peak UV season runs May - September, when the midday index typically reaches Very High (8-10).

How high does the UV index get in Boise?

Summer days in Boise typically reach Very High (8-10). Spring and fall usually bring Moderate to High (4-7), while winter values are typically Low (1-3).

Do I need sunscreen in Boise during winter?

In the valley, winter UV is low; on the slopes at Bogus Basin and beyond, snow reflection plus altitude make sunscreen and eye protection genuinely necessary.

How sunny is Boise compared to other cities?

Boise averages about 206 sunny days per year with an average annual UV index around 6.3.