Cobb Reservoir – current water temperature and swimming conditions
This page provides information about the current water temperature at Cobb Reservoir in Tasman 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 Cobb Reservoir today is 14°C.
Water Temperature in Cobb Reservoir: Daily Trends, Historical Records, and Forecast
⚠️ Lake temperatures between 10 and 15°C are cold but can be manageable for short swims on sunny, warm days. Shallow areas may feel slightly warmer, while deeper sections remain cold and slow to warm up. Most swimmers keep sessions brief, and wetsuits are often used for comfort. Wind and cooler air temperatures can quickly reduce how pleasant the swim feels.
Water Temperature Over the Last 30 Days
Over the past month, water temperatures in Cobb Reservoir have stayed mostly steady, but a warming trend has developed over the last week.
According to our forecast, the water temperature in Cobb Reservoir will be 15.7°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 | 13.0°C | 16.0°C | |
| Mar 23 | 13.0°C | 16.0°C | |
| Mar 24 | 13.0°C | 16.0°C | |
| Mar 25 | 13.0°C | 16.0°C | |
| Mar 26 | 13.2°C | 16.0°C | |
| Mar 27 | 13.2°C | 16.0°C | |
| Mar 28 | 13.3°C | 16.0°C | |
| Mar 29 | 13.3°C | 16.0°C | |
| Mar 30 | 13.6°C | 16.0°C | 13.6°C |
| Mar 31 | 16.0°C | 13.9°C | |
| Apr 1 | 16.0°C | 14.2°C | |
| Apr 2 | 16.0°C | 14.5°C | |
| Apr 3 | 16.0°C | 14.8°C | |
| Apr 4 | 16.0°C | 15.1°C | |
| Apr 5 | 16.0°C | 15.4°C | |
| Apr 6 | 16.0°C | 15.7°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 | 11°C | 18°C | 24°C |
| February | 9°C | 17°C | 24°C |
| March | 10°C | 16°C | 22°C |
| April | 9°C | 14°C | 18°C |
| May | 5°C | 10°C | 14°C |
| June | 2°C | 7°C | 12°C |
| July | 1°C | 6°C | 10°C |
| August | 3°C | 7°C | 11°C |
| September | 5°C | 9°C | 13°C |
| October | 7°C | 12°C | 16°C |
| November | 8°C | 14°C | 19°C |
| December | 9°C | 15°C | 21°C |
Cobb Reservoir: Weather Forecast
March 30
March 31
April 1
April 2
April 3
Location & Local Information
Cobb Reservoir, in the Tasman Region within Kahurangi National Park, is a high-country hydro lake set among open tussock and rugged mountains. Its elevation and alpine inflows influence water temperatures throughout the year. In winter, surface temperatures are generally around 4–8°C, with frost and occasional ice forming along the shoreline. During spring, snowmelt from surrounding peaks keeps the reservoir cold, typically between 6 and 10°C. In summer, particularly in January and February, sheltered near-shore areas may warm to approximately 11–16°C on calm, sunny days, while deeper water remains noticeably colder. By autumn, temperatures usually ease back to between 7 and 12°C. Strong winds can mix the surface and reduce comfort levels.
Swimming Conditions
Swimming is allowed at Cobb Reservoir, but it is uncommon due to the consistently cool conditions and remote setting. Even in mid-summer, the water can feel brisk, especially away from the shoreline. The most suitable time for a brief swim is during settled summer weather when temperatures approach the mid teens and winds are light. Swimmers should choose sheltered bays and enter gradually to reduce the risk of cold shock. Checking weather conditions beforehand helps ensure a safer and more comfortable experience in this exposed alpine environment.