Lake Ronkonkoma — Current Water Temperature, Annual Trends and Forecast
This page provides information on the current water temperature in Lake Ronkonkoma, trends, monthly ranges and the forecast for the coming days.
Current Water Temperature
Water Temperature in Lake Ronkonkoma today is 15.7°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 |
|---|---|---|---|
| OCT 5 | 18.6°C | 16.5°C | |
| OCT 6 | 18.2°C | 16.5°C | |
| OCT 7 | 17.9°C | 16.5°C | |
| OCT 8 | 17.2°C | 16.5°C | |
| OCT 9 | 16.7°C | 16.5°C | |
| OCT 10 | 17.2°C | 16.5°C | |
| OCT 11 | 17.1°C | 16.5°C | |
| OCT 12 | 16.0°C | 16.5°C | |
| OCT 13 | 16.5°C | 15.7°C | |
| OCT 14 | 16.5°C | 15.8°C | |
| OCT 15 | 16.5°C | 15.8°C | |
| OCT 16 | 16.5°C | 15.9°C | |
| OCT 17 | 16.5°C | 15.9°C | |
| OCT 18 | 16.5°C | 15.9°C | |
| OCT 19 | 16.5°C | 16.0°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 | 2°C | 4°C |
| February | 0°C | 2°C | 4°C |
| March | 0°C | 5°C | 10°C |
| April | 7°C | 12°C | 17°C |
| May | 11°C | 15°C | 20°C |
| June | 16°C | 20°C | 24°C |
| July | 22°C | 26°C | 29°C |
| August | 23°C | 26°C | 28°C |
| September | 20°C | 24°C | 27°C |
| October | 13°C | 17°C | 20°C |
| November | 6°C | 10°C | 13°C |
| December | 2°C | 6°C | 9°C |
Lake Ronkonkoma: Water Temperature by Location
Lake Ronkonkoma: Weather Forecast
October 13
October 14
October 15
October 16
October 17
October 18
Location & Local Information
Lake Ronkonkoma, the largest freshwater lake on Long Island, experiences a pronounced seasonal swing in surface water temperature. In winter months the lake often hovers near freezing, commonly around 33–40°F (1–4°C) and occasionally developing partial ice cover. Spring brings a steady warm-up, with surface temperatures typically rising from about 40–60°F (4–16°C) as air temperatures climb and stratification begins. During the peak of summer, July and August, surface temperatures are usually in the mid-to-upper 60s to upper 70s Fahrenheit, roughly 68–78°F (20–26°C), and can reach into the low 80s (about 27–28°C) on heatwave days. In fall the water cools again, falling through the 50s and 60s Fahrenheit, approximately 10–20°C.
Swimming at Lake Ronkonkoma is generally permitted in designated areas during the summer season when local parks or beaches post lifeguards and maintain facilities; these controlled areas exist because supervision, posted rules, and monitored water quality reduce risks. Outside the official swim season, open-water swimming is often discouraged due to colder temperatures, lack of lifeguards, potential water-quality variability, and underwater hazards such as sudden drop-offs and vegetation. Visitors should follow posted regulations and local advisories before entering the water.