McGregor Lake — Current Water Temperature, Annual Trends and Forecast
This page provides information on the current water temperature in McGregor Lake, trends, monthly ranges and the forecast for the coming days.
Current Water Temperature
Water Temperature in McGregor Lake today is 19.9°C.
Water Temperature: Daily Trends, Historical Records, and Forecast
⚠️ As of today, the minimum water temperature ranges from 65°F (18°C) to 68°F (20°C). This is already quite warm water, which is ideal for most people. Swimming becomes comfortable, and prolonged stays in the water do not cause discomfort. This temperature is perfect for family trips and for those who prefer warmer water. It is also comfortable for water sports such as surfing or swimming. 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 |
|---|---|---|---|
| AUG 24 | 20.3°C | 22.0°C | |
| AUG 25 | 20.2°C | 22.0°C | |
| AUG 26 | 20.6°C | 22.0°C | |
| AUG 27 | 20.5°C | 22.0°C | |
| AUG 28 | 20.5°C | 22.0°C | |
| AUG 29 | 20.3°C | 22.0°C | |
| AUG 30 | 20.3°C | 22.0°C | |
| AUG 31 | 20.2°C | 22.0°C | |
| SEP 1 | 18.0°C | 19.8°C | |
| SEP 2 | 18.0°C | 19.7°C | |
| SEP 3 | 18.0°C | 19.6°C | |
| SEP 4 | 18.0°C | 19.5°C | |
| SEP 5 | 18.0°C | 19.4°C | |
| SEP 6 | 18.0°C | 19.3°C | |
| SEP 7 | 18.0°C | 19.2°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 | 1°C | 4°C |
| February | 0°C | 3°C | 5°C |
| March | 0°C | 3°C | 6°C |
| April | 1°C | 4°C | 7°C |
| May | 3°C | 9°C | 16°C |
| June | 11°C | 15°C | 18°C |
| July | 14°C | 18°C | 23°C |
| August | 19°C | 22°C | 25°C |
| September | 15°C | 18°C | 21°C |
| October | 8°C | 13°C | 17°C |
| November | 2°C | 6°C | 9°C |
| December | 0°C | 2°C | 5°C |
McGregor Lake: Water Temperature by Location
McGregor Lake: Weather Forecast
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September 4
September 5
Location & Local Information
McGregor Lake in Montana experiences the same seasonal shifts in water temperature typical of mid-latitude inland lakes. After ice-out in spring surface temperatures often sit around 40–55°F (4–13°C) as snowmelt and cool inflows keep the water chilly. In summer, the shallow upper layers can warm to roughly 60–75°F (15–24°C) on sunny afternoons, with peak surface pockets occasionally reaching the upper 70s°F (~25°C) in long, hot spells; deeper water remains substantially cooler. By autumn the surface cools back to about 45–60°F (7–16°C) and eventually approaches freezing (32°F / 0°C) under winter ice. Local factors such as depth, inflowing streams, wind and recent weather will shift these ranges from year to year.
Swimming is generally allowed during the ice-free months because McGregor Lake is used for recreational purposes and is not uniformly closed to bathing, but access can be limited by private shoreline, boat traffic or posted rules. Typical comfortable swimming conditions are most likely in mid-summer when surface temperatures reach the mid‑60s to mid‑70s°F (18–24°C). Early- and late-season swimming carries risks from cold shock and hypothermia, and winter ice cover makes immersion dangerous. Always follow local signage, check for water-quality advisories, and take standard safety precautions such as wearing a life jacket when boating nearby.