Lake Grassmere – current water temperature and swimming conditions
This page provides information about the current water temperature at Lake Grassmere in Marlborough Region. 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 Grassmere today is 18°C.
Water Temperature in Lake Grassmere: 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
Over the past month, water temperatures in Lake Grassmere have stayed mostly steady, but a warming trend has developed over the last week.
According to our forecast, the water temperature in Lake Grassmere 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 22 | 15.4°C | 18.0°C | |
| Mar 23 | 15.4°C | 18.0°C | |
| Mar 24 | 15.4°C | 18.0°C | |
| Mar 25 | 15.4°C | 18.0°C | |
| Mar 26 | 17.2°C | 18.0°C | |
| Mar 27 | 17.2°C | 18.0°C | |
| Mar 28 | 17.3°C | 18.0°C | |
| Mar 29 | 17.3°C | 18.0°C | |
| Mar 30 | 17.7°C | 18.0°C | 17.7°C |
| Mar 31 | 18.0°C | 17.7°C | |
| Apr 1 | 18.0°C | 17.8°C | |
| Apr 2 | 18.0°C | 17.8°C | |
| Apr 3 | 18.0°C | 17.9°C | |
| Apr 4 | 18.0°C | 17.9°C | |
| Apr 5 | 18.0°C | 17.9°C | |
| Apr 6 | 18.0°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 | 15°C | 20°C | 25°C |
| February | 15°C | 20°C | 25°C |
| March | 14°C | 18°C | 22°C |
| April | 10°C | 15°C | 19°C |
| May | 7°C | 12°C | 17°C |
| June | 5°C | 10°C | 14°C |
| July | 5°C | 9°C | 12°C |
| August | 6°C | 9°C | 12°C |
| September | 7°C | 11°C | 15°C |
| October | 9°C | 14°C | 18°C |
| November | 10°C | 16°C | 22°C |
| December | 13°C | 19°C | 24°C |
Lake Grassmere: Weather Forecast
March 30
March 31
April 1
April 2
April 3
Location & Local Information
Lake Grassmere, also known as Kapara Te Hau, in the Marlborough Region near the east coast, is a shallow coastal lagoon separated from the sea by a narrow gravel barrier. Much of the surrounding area is used for salt production, and the lake’s shallow depth strongly influences its water temperature. In winter, surface temperatures are generally around 8–12°C. During spring, the lagoon gradually warms to approximately 12–18°C as air temperatures rise. In summer, particularly in January and February, shallow areas can reach about 20–26°C on hot, settled days. By autumn, temperatures usually ease back to between 14 and 19°C. Wind can quickly mix the shallow water and affect surface warmth.
Swimming Conditions
Swimming is not recommended at Lake Grassmere. Although summer water temperatures may feel warm enough for swimming, the lake is managed primarily for salt harvesting, and access to much of the area is restricted. Water salinity levels can also vary significantly, and conditions are not suited to recreational use. Visitors generally view the lake from roadside lookouts rather than entering the water. For most people, Lake Grassmere is appreciated for its unique landscape and saltworks rather than as a swimming destination.