Upper Jo-Mary Lake — Current Water Temperature, Annual Trends and Forecast
This page provides information on the current water temperature in Upper Jo-Mary Lake, trends, monthly ranges and the forecast for the coming days.
Current Water Temperature
Water Temperature in Upper Jo-Mary Lake today is 15.4°C.
Water Temperature: Daily Trends, Historical Records, and Forecast
⚠️ As of today, the minimum water temperature ranges from 60°F (15°C) to 65°F (18°C). The water is comfortable for most people, making it an ideal range for water sports enthusiasts. The temperature does not cause significant discomfort, and swimming will be pleasant for the majority. However, it's important to remember that prolonged exposure to the water can still lead to cooling, so it's essential to monitor the time spent in the water, especially for children or elderly people. 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 |
|---|---|---|---|
| JUN 3 | 10.3°C | 14.4°C | |
| JUN 4 | 10.6°C | 14.4°C | |
| JUN 5 | 11.0°C | 14.4°C | |
| JUN 6 | 11.6°C | 14.4°C | |
| JUN 7 | 14.8°C | 14.4°C | |
| JUN 8 | 14.9°C | 14.4°C | |
| JUN 10 | 15.4°C | 14.4°C | |
| JUN 11 | 14.4°C | 15.4°C | |
| JUN 12 | 14.4°C | 15.3°C | |
| JUN 13 | 14.4°C | 15.3°C | |
| JUN 14 | 14.4°C | 15.2°C | |
| JUN 15 | 14.4°C | 15.2°C | |
| JUN 16 | 14.4°C | 15.1°C | |
| JUN 17 | 14.4°C | 15.1°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 | 2°C | 7°C | 10°C |
| February | 2°C | 7°C | 12°C |
| March | 1°C | 8°C | 14°C |
| April | 1°C | 8°C | 15°C |
| May | 2°C | 10°C | 17°C |
| June | 10°C | 14°C | 18°C |
| July | 17°C | 22°C | 26°C |
| August | 21°C | 24°C | 26°C |
| September | 19°C | 23°C | 26°C |
| October | 10°C | 14°C | 18°C |
| November | 3°C | 8°C | 12°C |
| December | 3°C | 6°C | 8°C |
Upper Jo-Mary Lake: Water Temperature by Location
Upper Jo-Mary Lake: Weather Forecast
June 9
June 10
June 11
June 12
Location & Local Information
Upper Jo-Mary Lake, like many lakes in central and northern Maine, experiences strong seasonal temperature swings. In early spring the surface water commonly runs cool, roughly 40–55°F (4–13°C) as snowmelt and cold runoff dominate. By mid to late summer, surface temperatures typically warm to about 65–75°F (18–24°C) in warm years, though deeper or shaded bays can remain several degrees cooler. During autumn the surface falls back into the 45–60°F (7–16°C) range as air temperatures drop, and in winter the lake usually freezes or approaches near-freezing conditions with water at or just above 32°F (0°C) under ice cover.
Swimming is generally possible at Upper Jo-Mary where shoreline access exists, because the lake is used for recreation; there are no formal public beaches or lifeguarded facilities in many remote Maine lakes, so swimmers should assume unmonitored conditions. Cold water even in summer can increase risk of shock and hypothermia, and ice makes winter swimming hazardous; therefore safe swimming depends on choosing a sheltered, shallow spot, wearing appropriate gear, never swimming alone, and checking local signage or landowner rules for access restrictions. Recreational use by boaters and anglers is common, but safety and respect for private or conserved lands determine whether a particular spot is suitable for swimming.