Lake Chelan — Washington State
Lake Chelan
Water Temperature
Live readings from Chelan PUD dam monitoring, updated daily.
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Overview
Lake Chelan's water temperature is tracked daily at the Chelan PUD dam monitoring station at the base of the lake — the same station used for hydroelectric operations. Unlike most water temperature services that rely on weather models or satellite surface readings, this is actual in-lake data updated each afternoon. It's the most accurate available reading for Lake Chelan.
Lake Chelan has never fully frozen, though there are historical reports of a partial freeze from Chelan to Manson in the early 1900s. Winter surface temperatures hover in the high 30s to low 40s°F — cold but well above a full freeze, contrary to what many weather aggregators report. The warmest months are July through September, when the lower lake regularly reaches 70–73°F. By late September temperatures begin falling sharply as the lake cools toward winter.
Not all of Lake Chelan runs at the same temperature. The lower lake near Chelan and Manson — where the lake is shallower and more sheltered — warms fastest and runs warmest. The upper lake near Stehekin stays 5°F or more cooler throughout summer due to cold snowmelt flowing in from the North Cascades. The dam station reading reflects conditions at the Chelan end of the lake.
Water Temperature
Monthly average · °F
Twelve months of Lake Chelan
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Things to Know
Spring (Apr–Jun)
Temperatures climb from the low 40s in April to the low 60s by late June. The lake is cold but swimmable by May without a wetsuit — brisk rather than off-limits. Snowmelt keeps temps cool through June before the summer warmup begins.
Summer (Jul–Sep)
The prime swimming window. Surface temps peak at 70–73°F in August at the lower lake. Mid-July through early September is the warmest stretch and the best time to swim without a wetsuit.
Fall (Oct–Nov)
Temperatures drop quickly after Labor Day. By October the lake is back in the low 50s; by November in the mid-40s. Still swimmable, but wetsuit weather for most people.
Winter (Dec–Mar)
Surface temps settle into the high 30s to low 40s. The lake has never fully frozen — historical records note only a partial freeze from Chelan to Manson in the early 1900s. Other sites that report 32°F in winter are pulling from inaccurate models.
Lower vs. Upper Lake
The lower lake near Chelan and Manson runs 5°F or more warmer than the upper lake near Stehekin all summer. Cold snowmelt from the North Cascades feeds the upper lake continuously, keeping it noticeably cooler.
Wetsuit Threshold
Lake Chelan is swimmable without a wetsuit for most of the year — by May it is cold but manageable. Peak summer temps in the low 70s are comfortable for extended swimming. The upper lake near Stehekin runs cooler and may feel sharper even in July.
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