Marlborough Region – Water Temperature Overview
Marlborough Region features a coastline as well as numerous rivers and inland lakes. Water temperatures vary significantly by season and location, influencing swimming conditions across coastal and inland areas.
Current Sea Water Temperature
It’s important to note that these swimming tips and recommendations apply only in settled weather. When air temperatures drop below 20°C — and sometimes even below 25°C — swimming can feel uncomfortable, even when water temperatures are relatively high.
Sea Temperature Trends
Over the past month, the sea water temperature has remained largely unchanged. Overall, the sea water temperature is within the range expected based on historical data for this month.
Water Temperature and Swimming Conditions by Month
| Month | Min | Avg | Max |
|---|---|---|---|
| January | 14°C | 17°C | 19°C |
| February | 14°C | 17°C | 19°C |
| March | 14°C | 17°C | 19°C |
| April | 12°C | 15°C | 17°C |
| May | 11°C | 14°C | 17°C |
| June | 10°C | 13°C | 16°C |
| July | 10°C | 13°C | 15°C |
| August | 9°C | 12°C | 14°C |
| September | 10°C | 12°C | 14°C |
| October | 10°C | 13°C | 15°C |
| November | 11°C | 14°C | 16°C |
| December | 13°C | 16°C | 18°C |
Most Viewed Sea Places in the Marlborough Region
Current Water Temperature in Lakes and Rivers
About the Region & Location Map
Marlborough Region, at the north-eastern tip of the South Island, features a mix of open coastline and sheltered sounds, which influence local water temperatures. During summer, from December to February, sea temperatures typically range between 17°C and 20°C, with protected inlets in the Marlborough Sounds sometimes feeling slightly warmer on calm days. These conditions are generally suitable for swimming, particularly in sheltered bays where wave action is limited. In winter, coastal waters usually cool to around 12°C to 14°C. While that feels brisk, swimming is allowed year-round, and many people still enjoy short dips when conditions are settled. As always, it’s important to be aware of tides, currents and changing weather.
Inland, Marlborough’s rivers and lakes warm up during the sunny summer months. Freshwater temperatures often sit between 16°C and 21°C in mid to late summer, depending on river flow and lake depth. Smaller lakes and slower stretches of river can become pleasantly warm after prolonged sunshine. In winter, inland waters commonly drop to between 5°C and 11°C, especially in higher-altitude areas. Swimming is generally permitted where water quality is suitable and there are no health advisories, as heavy rainfall can temporarily affect clarity and bacterial levels. Overall, Marlborough provides a range of coastal and freshwater swimming options during the warmer part of the year.