Loch McNess – current water temperature and swimming conditions

This page provides information about the current water temperature at Loch McNess in Western Australia. 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

20.0°C

Today

19.9°C

Yesterday

19.8°C

A Week Ago

The water temperature in Loch McNess today is 20°C.

Water Temperature in Loch McNess: Daily Trends, Historical Records, and Forecast

Water Temperature Over the Last 30 Days

While water temperatures in Loch McNess declined overall during the past month, they have shown a noticeable rebound over the last week.

According to our forecast, the water temperature in Loch McNess will be 19.5°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
Aug 14	20.1°C	19.4°C
Aug 15	20.4°C	19.4°C
Aug 16	19.8°C	19.4°C
Aug 17	19.9°C	19.4°C
Aug 18	20.0°C	19.4°C
Aug 19	19.9°C	19.4°C
Aug 20	19.9°C	19.4°C
Aug 21	19.9°C	19.4°C
Aug 22	20.0°C	19.4°C	20.0°C
Aug 23		19.4°C	19.9°C
Aug 24		19.4°C	19.9°C
Aug 25		19.4°C	19.8°C
Aug 26		19.4°C	19.7°C
Aug 27		19.4°C	19.6°C
Aug 28		19.4°C	19.6°C
Aug 29		19.4°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 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	18°C	20°C	31°C
February	18°C	20°C	32°C
March	18°C	20°C	29°C
April	15°C	18°C	21°C
May	13°C	16°C	17°C
June	10°C	19°C	22°C
July	10°C	19°C	22°C
August	11°C	19°C	22°C
September	13°C	20°C	22°C
October	16°C	20°C	22°C
November	19°C	20°C	31°C
December	18°C	20°C	33°C

Location & Local Information

Loch McNess is a shallow freshwater lake within Yanchep National Park, north of Perth, and its water temperature reflects the local Mediterranean climate and groundwater influence. Because the lake is shallow, temperatures respond quickly to seasonal conditions. In summer, the water commonly warms to around 20–25°C, which can feel quite mild on hot days. Spring and autumn usually sit between 16–20°C, offering cooler but still moderate conditions. During winter, water temperatures often drop to about 12–15°C, giving the lake a noticeably cool feel, particularly in the mornings and after cold nights. Cloud cover and wind can also affect how warm the water feels from day to day.

Swimming Conditions

Swimming in Loch McNess is generally not recommended. While summer water temperatures may appear suitable, the lake is managed primarily for conservation and passive recreation rather than swimming. Water quality can vary due to nutrient levels, natural organic matter, and limited circulation, which can reduce clarity at times. The lake is also an important habitat for wildlife, including birds and aquatic species, and human swimming is discouraged to protect the environment. After rainfall, conditions can worsen further, with cooler water and reduced quality. Overall, Loch McNess is best enjoyed for walking, picnicking, and wildlife viewing, with its seasonal water temperatures noted but swimming avoided in favour of safer, designated waterways elsewhere in the region.

Nearby Lakes

Frequently Asked Questions

What is the current water temperature in Loch McNess?

The water temperature in Loch McNess today is 20°C.

What is the water temperature in Loch McNess during the summer months?

In summer, water temperatures in Loch McNess typically range from 18°C to 33°C.

Is it possible to swim in Loch McNess (Western Australia)?

You can swim in Loch McNess at Yanchep National Park when conditions permit, but access is sometimes seasonal or restricted — always check the park signage or ring the rangers to confirm current water quality and safety. The lake is groundwater‑fed and can be quite cool even in summer, and there may be submerged vegetation or algal blooms at times, so swim with a mate, take care and follow local advice.