Onaero – current water temperature and swimming conditions

This page shows the current water temperature at Onaero in Taranaki 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

18.7°C

Today

18.6°C

Yesterday

18.7°C

A Week Ago

The average sea water temperature today in Onaero is about 19°C.

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

⚠️ Water in this range feels cool but still manageable for many swimmers. Short to moderate swims are comfortable, especially in warm weather. Some people may prefer a wetsuit for longer stays, particularly when swimming actively or outside peak summer conditions.

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 February 27 to March 29

Water temperatures in Onaerofell over the past month, but have levelled out during the last week.

According to our forecast, Sea water temperature in Onaero will be 17.1°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
Mar 22	19.4°C	18.8°C
Mar 23	18.7°C	18.5°C
Mar 24	18.7°C	18.5°C
Mar 25	18.7°C	18.8°C
Mar 26	18.9°C	18.5°C
Mar 27	18.7°C	18.5°C
Mar 28	18.7°C	18.3°C
Mar 29	18.6°C	18.5°C
Mar 30	18.7°C	18.5°C	18.7°C
Mar 31		18.8°C	18.5°C
Apr 1		18.8°C	18.2°C
Apr 2		17.0°C	18.0°C
Apr 3		17.0°C	17.8°C
Apr 4		16.5°C	17.6°C
Apr 5		16.5°C	17.3°C
Apr 6		16.5°C	17.1°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 Onaero 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

Onaero is a small coastal settlement north of New Plymouth in the Taranaki Region, facing the Tasman Sea. Sea temperatures here follow the typical west coast pattern, with noticeable seasonal variation. In winter, from June to August, the water generally ranges between 11–14°C, which feels distinctly cold and is usually best suited to surfers or swimmers wearing full wetsuits. Through spring, temperatures gradually lift to around 13–15°C. Summer, from December to March, brings the most inviting conditions, with sea temperatures commonly sitting between 16–19°C during settled, sunny spells. Early autumn can still see 15–17°C before cooling again as winter approaches.

Monthly Water Temperature Range (Min, Max & Average)

Month	Min	Avg	Max
January	16°C	19°C	22°C
February	18°C	20°C	22°C
March	16°C	19°C	22°C
April	16°C	18°C	20°C
May	15°C	17°C	20°C
June	13°C	16°C	18°C
July	12°C	15°C	17°C
August	12°C	14°C	16°C
September	12°C	14°C	15°C
October	12°C	14°C	16°C
November	13°C	16°C	20°C
December	15°C	17°C	21°C

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

Onaero: Weather Forecast

March 30

14°C / 19°C

clear sky

humidity: 80% | wind: 18 kmh

March 31

11°C / 19°C

clear sky

humidity: 70% | wind: 18 kmh

April 1

10°C / 17°C

clear sky

humidity: 69% | wind: 7 kmh

April 2

11°C / 18°C

clear sky

humidity: 78% | wind: 7 kmh

Local Water Conditions and Nearby Spots

Swimming Conditions

Swimming is allowed at Onaero Beach and it’s a peaceful spot during the warmer months. The beach is a mix of sand and stones and sits in a small bay that can offer slightly more shelter than fully exposed stretches of coast. However, it remains open to Tasman Sea swells, and waves and rip currents can develop depending on wind and tide. There are generally no regular lifeguard patrols, so swimmers need to assess conditions carefully before entering the water. On calm summer days the water can be clear and refreshing, making it suitable for confident swimmers. Outside summer, cooler sea temperatures mean most people prefer thermal gear for longer swims.