Clear Lake — Current Water Temperature, Annual Trends and Forecast
This page provides information on the current water temperature in Clear Lake, trends, monthly ranges and the forecast for the coming days.
Current Water Temperature
Water Temperature in Clear Lake today is 18.2°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 |
|---|---|---|---|
| SEP 14 | 18.4°C | 20.6°C | |
| SEP 15 | 18.7°C | 20.6°C | |
| SEP 16 | 18.4°C | 20.6°C | |
| SEP 17 | 18.4°C | 20.6°C | |
| SEP 18 | 17.7°C | 20.6°C | |
| SEP 19 | 18.5°C | 20.6°C | |
| SEP 20 | 18.2°C | 20.6°C | |
| SEP 21 | 18.2°C | 20.6°C | |
| SEP 22 | 20.6°C | 18.3°C | |
| SEP 23 | 20.6°C | 18.4°C | |
| SEP 24 | 20.6°C | 18.6°C | |
| SEP 25 | 20.6°C | 18.7°C | |
| SEP 26 | 20.6°C | 18.8°C | |
| SEP 27 | 20.6°C | 18.9°C | |
| SEP 28 | 20.6°C | 19.0°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 | 1°C | 3°C | 6°C |
| March | 1°C | 4°C | 7°C |
| April | 4°C | 9°C | 14°C |
| May | 9°C | 15°C | 22°C |
| June | 16°C | 20°C | 24°C |
| July | 22°C | 26°C | 28°C |
| August | 20°C | 24°C | 28°C |
| September | 18°C | 21°C | 24°C |
| October | 9°C | 15°C | 20°C |
| November | 3°C | 7°C | 11°C |
| December | 1°C | 3°C | 6°C |
Clear Lake: Water Temperature by Location
Clear Lake: Weather Forecast
September 21
September 22
September 23
September 24
September 25
Location & Local Information
Clear Lake in north-central Iowa experiences wide seasonal swings in surface water temperature. In spring the lake typically ranges from about 45–60°F (7–16°C) as waters warm after ice-out, rising in summer to roughly 70–80°F (21–27°C) on average and occasionally into the mid-80s°F (around 29°C) on hot spells. Early fall brings cooling waters, commonly 50–65°F (10–18°C), and by late fall and winter the surface often approaches freezing, roughly 32–40°F (0–4°C), with ice cover possible during sustained cold periods. These figures refer to surface conditions; deeper layers remain cooler and change less quickly than the surface.
Swimming at Clear Lake is permitted in designated beach and park areas during the warmer months, with local authorities and park managers setting seasonal rules and posting advisories. Lifeguard coverage, posted hours, and access points vary, and water quality is routinely monitored; swimming may be temporarily restricted after heavy rains or when bacterial counts or harmful algal blooms (cyanobacteria) present a health risk. Cold-season activities such as ice fishing occur when conditions are safe, but winter swimming carries hypothermia and thin-ice dangers and is generally discouraged except in organized, well-prepared events with proper safety measures.