Diablo & Ross Lakes, WA

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Diablo Lake in the North Cascade Mountains

Today’s Forecast:

🌤
43°F
High: 57° | Low: 43°
Current Temperature
Station: HZCW1
Observed at: 11:23 am CST on 11/12/26
Wind: 0 mph | Humidity: 99%
Today:Mostly cloudy. High near 57, with temperatures falling to around 52 in the afternoon. Northeast wind 6 to 9 mph.
Tonight:Mostly cloudy, with a low around 45. East southeast wind 10 to 14 mph, with gusts as high as 29 mph.
Friday:Rain after 10am. Mostly cloudy. High near 57, with temperatures falling to around 52 in the afternoon. East southeast wind 9 to 14 mph, with gusts as high as 28 mph. Chance of precipitation is 80%. New rainfall amounts less than a tenth of an inch possible.
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Today’s Report:

🛶 Paddling

  11 /100

Not Recommended for paddling. High near 57°F. Rain forecast later today (81%). Breezy winds (14 mph). Temperatures outside comfort limits (57°F).

  • Temp: Unfavorable weather factor
  • Rain: Marginal weather factor
  • Wind: Marginal weather factor
  • Thunderstorm: Favorable conditions
Tomorrow's Outlook:
Not Recommended 4/100
Not Recommended for paddling. High near 46°F. High rain probability (57%). Temperatures outside comfort limits (46°F).

⛵ Boating

  12 /100

Not Recommended for boating. High near 57°F. Rain forecast later today (81%). Breezy winds (14 mph). Temperatures outside comfort limits (57°F).

  • Temp: Unfavorable weather factor
  • Rain: Marginal weather factor
  • Wind: Marginal weather factor
  • Thunderstorm: Favorable conditions
Tomorrow's Outlook:
Not Recommended 12/100
Not Recommended for boating. High near 46°F. Risk of rain (57%). Temperatures outside comfort limits (46°F).

⛺ Camping

Use Caution
  46 /100

Use Caution for camping. High near 57°F. Rain forecast later today (81%). Light wind (14 mph).

  • Temp: Favorable conditions
  • Rain: Marginal weather factor
  • Wind: Favorable conditions
  • Thunderstorm: Favorable conditions
Tomorrow's Outlook:
Use Caution 41/100
Use Caution for camping. High near 46°F. Risk of rain (57%).

About Diablo & Ross Lakes

Diablo & Ross Lakes is a Washington destination for turquoise reservoirs, overlooks, boat routes, remote camps, and Highway 20 access through the North Cascades.

Make the Most of a Diablo & Ross Lakes Day

Cold water, canyon wind, smoke, and limited landing options deserve extra margin. Verify boat transport and remote access before relying on them.

Weather Tips for Diablo & Ross Lakes

  • Compare valley and high-elevation forecasts because snow, wind, clouds, smoke, and temperature can change sharply with elevation.
  • Cold water, waves, current, wind, and lightning should guide water plans more than sunshine alone.
  • Check overnight lows, wet ground, fire rules, drainage, and the nearest substantial shelter before settling into camp.
  • Summer smoke, winter access, shoulder-season closures, and shorter fall daylight can matter even during an otherwise mild forecast.

Nearby Towns and Areas

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

  • Diablo Lake Overlook
  • Newhalem
  • Colonial Creek Campground
  • Ross Dam
  • Thunder Creek
  • North Cascades Highway
  • Hozomeen

Plan Around the Conditions

Use the forecast to choose the best version of a Diablo & Ross Lakes day. Match wind, precipitation, smoke, water conditions, trail surfaces, road access, temperature, and daylight to the activity that gives your group the safest and most comfortable plan.

7-Day Forecast for Diablo & Ross Lakes

🌤
43°F
High: 57° | Low: 43°
Current Temperature
Station: HZCW1
Observed at: 11:23 am CST on 11/12/26
Wind: 0 mph | Humidity: 99%
Thu ☁
57° 45°
2%
Fri 🌧
57° 44°
81%
Sat 🌧
51° 43°
71%
Sun 🌧
50° 40°
100%
Mon ❄
49° 37°
53%
Tue ⛅
49° 36°
12%
Wed ❄
48° 35°
21%

7-Day High Temperature Trend

57° Thu 57° Fri 51° Sat 50° Sun 49° Mon 49° Tue 48° Wed

7-Day Low Temperature Trend

45° Thu 44° Fri 43° Sat 40° Sun 37° Mon 36° Tue 35° Wed

📊 7-Day Outdoor Outlook

Good Fair Poor 100 Thu 93 Fri 69 Sat 62 Sun 19 Mon 20 Tue 20 Wed
Forecast data from the National Weather Service  |  Last Updated: November 12, 2026 9:37 pm CST

Diablo & Ross Lakes Weather by Season

Winter

Winter at Diablo & Ross Lakes brings mountain snow, ice, short daylight, and changing road or trailhead access. Higher routes may close while lower valleys remain rainy, so check current transportation notices.

Spring

Spring around Diablo & Ross Lakes brings changing conditions, rising rivers, wet trails, and lingering mountain snow. Cold water from rain and snowmelt remains a major planning factor. Mountain and eastern thunderstorms become increasingly possible later in the season.

Summer

Summer at Diablo & Ross Lakes is usually the driest and most dependable season, but wildfire smoke, fire restrictions, heat, and afternoon thunderstorms can interrupt plans. Use calmer mornings for boating or paddling and keep a shore-based backup. Dry vegetation makes local fire rules especially important.

Fall

Fall at Diablo & Ross Lakes brings cooler temperatures, shorter daylight, changing color, and the return of wetter weather west of the Cascades. Water cools faster than the air, increasing cold-water consequences. Check seasonal facility hours and allow extra time on busy event or salmon-viewing weekends.

Key Climate Data Points

  • Annual average temperature: around 45–49°F near reservoir level, using the relevant local or regional elevation context.
  • Annual snowfall: snowfall is moderate near the water and very heavy on surrounding Cascade slopes, with substantial year-to-year and elevation variation.
  • Warmest months: July and August are normally warmest.
  • Coolest months: December and January are typically coolest.
  • Wettest season: November through January.
  • Driest season: July and August.
  • Best outdoor window: June through September for boating and camping.