Boise Cascade Lake — Current Water Temperature, Annual Trends and Forecast
This page provides information on the current water temperature in Boise Cascade Lake, trends, monthly ranges and the forecast for the coming days.
Current Water Temperature
Water Temperature in Boise Cascade Lake today is 27.5°C.
Water Temperature: Daily Trends, Historical Records, and Forecast
✅ As of today, the minimum water temperature ranges from 79°F (26°C) to 82°F (28°C). This is very warm water, allowing for extended stays without any discomfort. Swimming in these conditions will be particularly enjoyable, making it the ideal temperature range for those who want to relax in the sea. Additionally, water in this temperature range is suitable for children and elderly people, as it is comfortable for prolonged stays. It is important to note that these swimming tips and recommendations apply only in good weather. When the air temperature is below 68°F (20°C), and sometimes even below 77°F (25°C), swimming can be unpleasant even with relatively high water temperatures.
Water Temperature Chart Over the Last 30 Days
Table of Daily Sea Temperature Data
| Date | Current | Average | Forecast |
|---|---|---|---|
| JUL 14 | 26.1°C | 24.2°C | |
| JUL 15 | 28.3°C | 24.2°C | |
| JUL 16 | 28.4°C | 24.2°C | |
| JUL 17 | 28.4°C | 24.2°C | |
| JUL 18 | 27.8°C | 24.2°C | |
| JUL 19 | 27.5°C | 24.2°C | |
| JUL 20 | 27.6°C | 24.2°C | |
| JUL 21 | 27.6°C | 24.2°C | |
| JUL 22 | 24.2°C | 27.3°C | |
| JUL 23 | 24.2°C | 27.2°C | |
| JUL 24 | 24.2°C | 27.0°C | |
| JUL 25 | 24.2°C | 26.8°C | |
| JUL 26 | 24.2°C | 26.7°C | |
| JUL 27 | 24.2°C | 26.5°C | |
| JUL 28 | 24.2°C | 26.3°C |
* Current - Actual water temperature value
** Average - Average water temperature on this day in recent years
*** Forecast - Our water temperature forecast
Actual nearshore water temperatures may fluctuate by several degrees from the reported values, especially following heavy rainfall or extended periods of strong winds. Certain wind patterns can cause colder, deeper waters to rise and replace the sun-warmed surface water, leading to noticeable variations.
Our forecast is based on a proprietary mathematical model that considers real-time water temperature changes, historical trends, key weather patterns, wind strength and direction, and air temperature specific to each region. Additionally, we incorporate data from other resorts to enhance accuracy.
Monthly Water Temperature Range (Min, Max & Average)
| Month | Min | Avg | Max |
|---|---|---|---|
| January | 0°C | 2°C | 5°C |
| February | 1°C | 3°C | 6°C |
| March | 4°C | 7°C | 11°C |
| April | 6°C | 10°C | 14°C |
| May | 12°C | 16°C | 21°C |
| June | 16°C | 19°C | 23°C |
| July | 20°C | 24°C | 29°C |
| August | 19°C | 22°C | 25°C |
| September | 18°C | 21°C | 24°C |
| October | 12°C | 17°C | 21°C |
| November | 6°C | 9°C | 12°C |
| December | 0°C | 3°C | 7°C |
Boise Cascade Lake: Water Temperature by Location
Boise Cascade Lake: Weather Forecast
July 22
July 23
July 24
July 25
July 26
July 27
Location & Local Information
Lake Cascade (often called Cascade Reservoir) in central Idaho experiences a broad range of water temperatures through the year. In spring the surface water typically runs cool, roughly 40–55°F (4–13°C) as snowmelt feeds the reservoir. By summer, especially in July and August, surface temperatures commonly warm to about 65–75°F (18–24°C) on sunny days, although deeper water stays much colder. In early fall the lake cools back to roughly 50–60°F (10–16°C), and in winter surface temperatures hover near freezing, around 32–40°F (0–4°C), with ice forming in some sheltered bays when conditions permit.
Swimming is commonly done in the warm months but is essentially allowed at one’s own risk rather than being universally supervised; there are public beaches and campgrounds where people swim, yet official lifeguards are not always present and local rules can vary. Swimmers should be mindful of cold subsurface layers, boat traffic and changing weather, and potential water-quality advisories such as algal blooms at times of low flow or high temperatures. Because of these factors and the reservoir’s seasonal temperature shifts, summer provides the most comfortable and practical window for recreational swimming.