Best Time for North Cascade Loop

Last updated: 2026-09-20

Preferred months for this journey: June, July, August, September. Check the seasonal notes before choosing your dates.

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	❄