Lake Illawarra – current water temperature and swimming conditions
This page provides information about the current water temperature at Lake Illawarra in New South Wales. Here you can view recent temperature trends on a 30-day chart, check typical monthly water temperature ranges, and compare today’s reading with historical averages for this date. A 7-day water temperature forecast, local weather conditions, and an overview of swimming suitability are also included.
Current Water Temperature
The water temperature in Lake Illawarra today is 20°C.
Water Temperature in Lake Illawarra: Daily Trends, Historical Records, and Forecast
⚠️ A lake temperature of 15 to 20°C is considered cool to comfortable for swimming in Australia. On warm days with light winds, this range allows for relaxed swimming, especially in shallow or sheltered areas. Comfort depends strongly on air temperature and sunshine, as cooler or overcast weather can still make the water feel chilly. This range is common during spring and early summer.
Water Temperature Over the Last 30 Days
While water temperatures in Lake Illawarra declined overall during the past month, they have shown a noticeable rebound over the last week.
According to our forecast, the water temperature in Lake Illawarra will be 18.0°C in the next 7 days. See the table below for daily data for the upcoming week.
Table of Daily Water Temperature Data
| Date | Current | Average | Forecast |
|---|---|---|---|
| Mar 12 | 20.8°C | 17.8°C | |
| Mar 13 | 20.8°C | 17.8°C | |
| Mar 14 | 18.7°C | 17.8°C | |
| Mar 15 | 18.6°C | 17.8°C | |
| Mar 16 | 20.6°C | 17.8°C | |
| Mar 17 | 20.6°C | 17.8°C | |
| Mar 18 | 20.3°C | 17.8°C | |
| Mar 19 | 20.0°C | 17.8°C | |
| Mar 20 | 19.9°C | 17.8°C | 19.9°C |
| Mar 21 | 17.8°C | 19.6°C | |
| Mar 22 | 17.8°C | 19.4°C | |
| Mar 23 | 17.8°C | 19.1°C | |
| Mar 24 | 17.8°C | 18.8°C | |
| Mar 25 | 17.8°C | 18.5°C | |
| Mar 26 | 17.8°C | 18.3°C | |
| Mar 27 | 17.8°C | 18.0°C |
* Current - Actual water temperature value
** Average - Average water temperature on this day in recent years
*** Forecast - Our water temperature forecast
Actual lake water temperatures may differ from the reported values by several degrees, particularly during periods of strong winds or rapid weather changes. Wind can mix surface and deeper layers in a lake, bringing cooler water to the surface, while shallow areas may warm more quickly under direct sunlight. Air temperature, sunshine, and cloud cover strongly influence how quickly a lake heats up or cools down. These factors can lead to noticeable temperature variations across different parts of the lake.
Our forecast is based on a proprietary mathematical model that considers real-time lake temperature observations, historical trends, seasonal cycles, wind strength and direction, and region-specific air temperature. To enhance accuracy, we also incorporate data from nearby monitored locations and comparable lakes within Australia.
Monthly Water Temperature Range (Min, Max & Average)
| Month | Today | Yesterday | A Week Ago |
|---|---|---|---|
| January | 17°C | 20°C | 24°C |
| February | 17°C | 19°C | 22°C |
| March | 15°C | 18°C | 21°C |
| April | 13°C | 15°C | 19°C |
| May | 10°C | 12°C | 15°C |
| June | 8°C | 10°C | 12°C |
| July | 8°C | 9°C | 11°C |
| August | 8°C | 10°C | 12°C |
| September | 10°C | 11°C | 15°C |
| October | 11°C | 14°C | 18°C |
| November | 14°C | 17°C | 21°C |
| December | 16°C | 19°C | 22°C |
Lake Illawarra: Water Temperature by Location
Location & Local Information
Lake Illawarra is a broad coastal lagoon south of Sydney, sheltered from the open ocean and influenced mainly by local weather and seasonal conditions. Water temperature in the lake is generally moderate and fairly stable through the year. In summer, the lake usually warms to around 22–26°C, which feels comfortably warm and well suited to swimming. Spring and autumn tend to sit between 18–22°C, remaining pleasant on sunny days. During winter, water temperatures commonly drop to about 15–18°C, cool but still milder than many inland lakes or rivers in southern New South Wales.
Swimming Conditions
Swimming in Lake Illawarra is generally allowed and popular in suitable areas, particularly during the warmer months. Calm, shallow sections away from main channels are favoured, as they offer gentle conditions and easier access. The lake’s sheltered nature means there are no waves, and currents are usually mild, which suits casual swimming and family use. Water quality is typically good during dry periods, though it can be affected after heavy rain when runoff reduces clarity and slightly lowers temperatures. At those times, swimmers often wait for conditions to settle. Overall, Lake Illawarra provides reliable seasonal swimming opportunities, offering warm, protected water as a relaxed alternative to the nearby surf beaches.