Onetahuti – current water temperature and swimming conditions

This page shows the current water temperature at Onetahuti in Tasman Region. You can view recent sea temperature trends on a 30-day chart, check typical monthly water temperature ranges, and compare today’s reading with historical averages for this date. The page also includes a 7-day water temperature forecast, nearby beaches with similar conditions, local weather information, and a summary of swimming conditions to help you assess how suitable the water is for swimming.

Current Sea Water Temperature

13.2°C

Today

13.2°C

Yesterday

13.3°C

A Week Ago

The average sea water temperature today in Onetahuti is about 13°C.

Water Temperature in Onetahuti: Daily Trends, Historical Records, and Forecast

❌ Water at this temperature feels cold and is generally suitable only for brief immersion. Swimming without a wetsuit can quickly become uncomfortable, and exposure time is usually short. These conditions are mainly suitable for experienced swimmers or those using proper thermal gear.

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.

Water Temperature Over the Last 30 Days

From June 10 to July 10

Water temperatures in Onetahuti have been gradually cooling over the past month, with a further drop recorded during the last week.

According to our forecast, Sea water temperature in Onetahuti will be 12.6°C in the next 7 days. See the table below for daily data for the upcoming week.

Table of Daily Sea Temperature Data

Date	Current	Average	Forecast
Jul 2	13.5°C	13.0°C
Jul 3	13.5°C	12.8°C
Jul 4	13.3°C	12.8°C
Jul 5	13.3°C	12.5°C
Jul 6	13.3°C	12.3°C
Jul 7	13.3°C	12.5°C
Jul 8	13.3°C	12.8°C
Jul 9	13.2°C	12.8°C
Jul 10	13.2°C	12.8°C	13.2°C
Jul 11		11.8°C	13.1°C
Jul 12		11.5°C	13.0°C
Jul 13		11.8°C	12.9°C
Jul 14		12.0°C	12.8°C
Jul 15		11.8°C	12.8°C
Jul 16		12.3°C	12.7°C
Jul 17		12.3°C	12.6°C

* Current - Actual water temperature value

** Average - Average water temperature on this day in recent years

*** Forecast - Our water temperature forecast

Actual near-shore water temperatures in Onetahuti can vary by several degrees from the values shown, particularly after heavy rain, strong southerlies, or prolonged windy conditions. Certain wind patterns can trigger upwelling, where cooler, deeper water is pushed to the surface and replaces the warmer top layer, leading to noticeable short-term changes in water temperature.

Our water temperature forecast is produced using a proprietary mathematical model that combines real-time measurements with long-term historical patterns, local weather conditions, wind strength and direction, and air temperature specific to each coastal region. To improve accuracy, we cross-check data from nearby locations and use multiple sources, including offshore buoys, satellite-based sea surface maps, and observations provided by local authorities.

Annual Water Temperature Overview by Month

Monthly Water Temp Ranges

30°C

25°C

20°C

15°C

10°c

5°C

0°C

Annual Water Temperature Trend

Onetahuti Beach is a wide, golden stretch of sand in Abel Tasman National Park in the Tasman Region, opening into Tasman Bay and influenced by tidal flows connected to Cook Strait. Thanks to its northern location and relatively sheltered setting, water temperatures here are among the warmest in the South Island. In winter, from June to August, the sea typically ranges between 11–14°C, which feels cool and is usually comfortable only for short swims or with a wetsuit. Through spring, temperatures gradually rise to around 13–16°C. Summer, from December to March, brings the warmest conditions, with water temperatures commonly sitting between 18–22°C during settled, sunny spells. Early autumn can still see 17–19°C before cooling again as winter approaches.

Monthly Water Temperature Range (Min, Max & Average)

Month	Min	Avg	Max
January	14°C	16°C	19°C
February	14°C	17°C	19°C
March	14°C	16°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	12°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	15°C	18°C

* Click on a month to view detailed water temperature data.

Onetahuti: Weather Forecast

July 11

2°C / 10°C

clear sky

humidity: 82% | wind: 4 kmh

July 12

6°C / 11°C

light rain

humidity: 87% | wind: 4 kmh

July 13

11°C / 12°C

light rain

humidity: 91% | wind: 11 kmh

July 14

8°C / 14°C

few clouds: 11-25%

humidity: 88% | wind: 7 kmh

Local Water Conditions and Nearby Spots

Swimming Conditions

Swimming is allowed at Onetahuti and it’s a popular activity for walkers and kayakers exploring the park. The beach is gently sloping and sandy, and the bay is relatively protected from large ocean swells, often resulting in calm, clear water on fine days. Tidal movement is noticeable, especially at low tide when broad sand flats are exposed. There are no regular lifeguard patrols, so swimmers should assess conditions carefully before entering. On warm summer days, the water can feel pleasant and suitable for families and casual swimmers. Outside the warmer season, thermal gear may be preferred, though the bay remains comparatively mild year-round.