Lake Powell Water Temperature
The latest satellite pass reads Lake Powell's open-water surface at about 87 °F (August 17, 2026). Lake Powell's surface temperature peaks at 78–82 °F in July and August and bottoms out in the mid-40s °F in winter. Swimming is comfortable from roughly mid-June through September. Below Glen Canyon Dam it's a different story — the river releases stay cold (typically 46–60 °F) because they're drawn from deep in the reservoir.
Open-water average from the latest cloud-free satellite pass — captured August 17, 2026 via Landsat thermal imagery . Shallow coves run several degrees warmer; the deep water near Glen Canyon Dam stays coolest.
Typical for August: Lake Powell's surface water usually runs 78–82 °F — warm enough for comfortable, extended swimming. Actual readings shift a few degrees with weather, wind, and where you are on the lake; shallow coves run warmest and the deep water near the dam stays coolest.
Typical surface temperature by month
Long-term typical ranges for open-water surface temperature (NPS visitor guidance and historical readings). Actual readings vary with weather, wind mixing, and location on the lake.
| Month | Surface temp | Swimming |
|---|---|---|
| January | 46–49 °F | Too cold |
| February | 45–48 °F | Too cold |
| March | 48–54 °F | Too cold |
| April | 54–62 °F | Wetsuit only |
| May | 62–68 °F | Brisk |
| June | 70–76 °F | Comfortable |
| July | 78–82 °F | Ideal |
| August (this month) | 78–82 °F | Ideal |
| September | 72–77 °F | Comfortable |
| October | 63–68 °F | Brisk |
| November | 54–60 °F | Wetsuit only |
| December | 48–52 °F | Too cold |
Below the dam: a cold-water warning
The Colorado River immediately below Glen Canyon Dam is dramatically colder than the lake surface, because
releases are drawn from penstocks more than 200 feet down where the water stays cold all year.
Water temperature also interacts with lake level: in low-water years the warm surface layer sits closer to the penstocks, which is one reason release temperatures get monitored closely. USGS thermal monitoring recorded a record-warm average summer intake temperature of 66.6 °F in 2022, when the lake was just 25.4% full. See today's elevation on the live tracker and the seasonal rise and fall on the water level chart.
Sources: Landsat 8/9 surface temperature via Microsoft Planetary Computer (satellite surface reading), USGS gage 09380000 (Colorado River at Lees Ferry) , USGS Lake Powell thermal-profile monitoring , National Park Service — Glen Canyon NRA , and the National Center for Cold Water Safety .
Water Temperature FAQ
How warm is Lake Powell in summer?
Surface water peaks at roughly 78–82 °F in July and August — comparable to a swimming pool. June and September typically run in the low-to-mid 70s.
What is Lake Powell's water temperature right now?
The latest satellite reading (Landsat, August 17, 2026) puts Lake Powell's open-water surface at about 87 °F. Typical for August is 78–82 °F — warm enough for comfortable, extended swimming. Readings shift a few degrees with weather, wind, and location: shallow coves run warmest and the deep water near Glen Canyon Dam stays coolest. Below the dam, the Colorado River release is far colder (typically 46–60 °F year-round).
When is Lake Powell warm enough to swim?
Most swimmers find the lake comfortable from mid-June through September, when surface temperatures hold above about 70 °F. May and October are doable for the tolerant; the rest of the year calls for a wetsuit.
Is 70 °F lake water cold for swimming?
Technically, yes. The National Center for Cold Water Safety classifies any water below 70 °F as cold, and 60–70 °F as carrying real cold-shock risk. Lake Powell's surface only clears the 70 °F mark from about mid-June through September, so spring and fall swimmers should expect a cold entry even on a hot day.
Does Lake Powell's water level affect its temperature?
Yes, especially below the dam. As the reservoir drops, the warm surface layer sits closer to the penstock intakes, so release temperatures climb. USGS monitoring recorded a record-warm average summer intake temperature of 66.6 °F in 2022, when Lake Powell was just 25.4% full — warmer releases that concern biologists managing the cold-water trout fishery downstream.
Where is the water warmest at Lake Powell?
Shallow, sheltered spots — side canyons, back-of-cove beaches, and Lone Rock — warm fastest and can read into the mid-80s °F on a hot summer afternoon, several degrees above the open main channel. The coldest surface water is near Glen Canyon Dam and over the deep main channel.
Why is the water below Glen Canyon Dam so cold?
Releases are drawn from penstocks deep in the reservoir, where water stays cold year-round. The Colorado River at Lees Ferry below the dam typically runs 46–60 °F even in mid-summer — a shock compared to the lake's 80 °F surface.
Does the water temperature vary around the lake?
Yes. Shallow bays, beaches, and side canyons warm several degrees above the main channel in summer, while the deep water near the dam stays cooler. Wind mixing after storms can also drop surface readings temporarily.
Updated August 20, 2026 · Elevation data: U.S. Bureau of Reclamation (USBR). Ramp status: National Park Service (NPS). Informational only — verify conditions with official sources.