Lake Byllesby — Current Water Temperature, Annual Trends and Forecast
This page provides information on the current water temperature in Lake Byllesby, trends, monthly ranges and the forecast for the coming days.
Current Water Temperature
Water Temperature in Lake Byllesby today is 19.1°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 13 | 21.7°C | 20.3°C | |
| SEP 14 | 22.1°C | 20.3°C | |
| SEP 15 | 21.4°C | 20.3°C | |
| SEP 16 | 20.5°C | 20.3°C | |
| SEP 17 | 19.5°C | 20.3°C | |
| SEP 18 | 19.5°C | 20.3°C | |
| SEP 19 | 19.4°C | 20.3°C | |
| SEP 20 | 19.7°C | 20.3°C | |
| SEP 21 | 20.3°C | 19.2°C | |
| SEP 22 | 20.3°C | 19.2°C | |
| SEP 23 | 20.3°C | 19.3°C | |
| SEP 24 | 20.3°C | 19.3°C | |
| SEP 25 | 20.3°C | 19.4°C | |
| SEP 26 | 20.3°C | 19.5°C | |
| SEP 27 | 20.3°C | 19.5°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 | 2°C | 4°C |
| March | 0°C | 3°C | 5°C |
| April | 4°C | 10°C | 16°C |
| May | 11°C | 17°C | 22°C |
| June | 16°C | 22°C | 27°C |
| July | 21°C | 25°C | 30°C |
| August | 21°C | 25°C | 30°C |
| September | 17°C | 20°C | 24°C |
| October | 6°C | 13°C | 20°C |
| November | 3°C | 7°C | 11°C |
| December | 0°C | 3°C | 6°C |
Lake Byllesby: Water Temperature by Location
Lake Byllesby: Weather Forecast
September 21
September 22
September 23
September 24
September 25
September 26
Location & Local Information
Lake Byllesby’s surface temperatures vary with the seasons in ways typical of southern Minnesota lakes. In spring (April–May) surface readings commonly run about 40–60°F (4–16°C) as the water slowly warms. Summer highs in June through August are the most comfortable for swimmers, often ranging from roughly 68–80°F (20–27°C) at the surface on warm days. In fall (September–November) temperatures fall back into the 45–65°F (7–18°C) band. In winter the open water surface usually approaches freezing, around 32–35°F (0–2°C) where ice forms. Deeper parts of the reservoir stay appreciably colder than the surface; thermoclines and sudden temperature drops of 10°F (6°C) or more are common, so conditions can change with depth and weather.
Swimming is permitted at designated public beaches and managed park areas on the lake when conditions allow, primarily during the warmer months when surface temperatures are comfortable and water-quality testing shows no advisories. Spring and fall water is often too cool for prolonged swimming without protective gear, and winter ice makes open-water swimming unsafe for most people. Visitors should heed posted signs and local advisories because closures may be issued for bacterial or algal concerns, and cold water near depth changes presents a risk of cold shock and hypothermia even on warm days.