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Best Time for North Cascade Loop
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Sweet spot: April, May, June. Computed from NASA POWER climate normals across the route's overnight towns, balancing temperature, rainfall and daylight.
💡 Good to know
- The full loop is generated only after you confirm that SR 20 is open through Washington and Rainy passes. Opening dates vary, and a June calendar label is not proof that the road or a trail is usable.
- The strongest full-loop window, but wildfire, rockfall, snow and road works can still close SR 20 or park areas. Check WSDOT and North Cascades National Park before crossing the mountains.
- This full Cascade loop is not generated from October through May. SR 20 has a variable seasonal closure and can reopen late; a Leavenworth winter visit or a dated shoulder-season crossing needs a separately researched plan.
| Month | Low | High | Rain | Daylight | |
|---|---|---|---|---|---|
| January | −5.8°C | 0.5°C | 155 mm | 8.6 h | ❄ |
| February | −5.9°C | 1.6°C | 96 mm | 9.9 h | ❄ |
| March | −3.3°C | 4.5°C | 122 mm | 11.6 h | ❄ |
| April | −0.6°C | 8.3°C | 77 mm | 13.4 h | ❄ |
| May | 4.0°C | 14.7°C | 66 mm | 14.9 h | |
| June | 7.1°C | 18.3°C | 50 mm | 15.9 h | |
| July | 10.2°C | 22.8°C | 21 mm | 15.5 h | |
| August | 10.2°C | 22.6°C | 26 mm | 14.1 h | |
| September | 6.8°C | 18.2°C | 50 mm | 12.3 h | |
| October | 1.9°C | 10.8°C | 113 mm | 10.6 h | ❄ |
| November | −2.5°C | 3.9°C | 164 mm | 8.9 h | ❄ |
| December | −6.3°C | −0.2°C | 157 mm | 8.1 h | ❄ |