Nine Mile – current water temperature and swimming conditions

This page shows the current water temperature at Nine Mile in West Coast 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

15.6°C

Today

15.8°C

Yesterday

15.9°C

A Week Ago

The average sea water temperature today in Nine Mile is about 16°C.

Water Temperature in Nine Mile: Daily Trends, Historical Records, and Forecast

⚠️ This is cool water that may feel brisk on entry. Swimming is usually limited to short sessions, and prolonged stays can become uncomfortable without thermal protection. Many swimmers choose a wetsuit, especially for surfing or open-water swimming.

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 April 14 to May 14

Water temperatures in Nine Mile 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 Nine Mile will be 15.5°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
May 6	15.8°C	15.5°C
May 7	15.8°C	15.5°C
May 8	15.9°C	15.5°C
May 9	15.8°C	15.8°C
May 10	15.8°C	15.8°C
May 11	15.9°C	15.3°C
May 12	16.0°C	15.5°C
May 13	15.8°C	15.5°C
May 14	15.6°C	15.5°C	15.6°C
May 15		15.5°C	15.6°C
May 16		15.0°C	15.6°C
May 17		15.8°C	15.6°C
May 18		14.5°C	15.6°C
May 19		15.3°C	15.6°C
May 20		15.5°C	15.5°C
May 21		15.3°C	15.5°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 Nine Mile 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

Nine Mile Beach, just north of Greymouth in the West Coast Region, stretches along the open Tasman Sea and is known for its long, wild shoreline. Sea temperatures here follow the typical West Coast pattern. In winter, from June to August, the water generally ranges between 11–14°C, which feels distinctly cold and is usually only comfortable for surfers or swimmers wearing full wetsuits. Through spring, temperatures gradually rise to around 13–15°C. Summer, from December to March, brings the most settled conditions, with sea temperatures commonly sitting between 16–19°C during fine 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	15°C	18°C	21°C
February	15°C	19°C	21°C
March	15°C	18°C	21°C
April	14°C	16°C	20°C
May	13°C	15°C	18°C
June	12°C	14°C	16°C
July	11°C	13°C	15°C
August	11°C	13°C	14°C
September	11°C	13°C	14°C
October	11°C	14°C	16°C
November	12°C	15°C	18°C
December	14°C	16°C	20°C

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

Nine Mile: Weather Forecast

May 15

8°C / 13°C

clear sky

humidity: 77% | wind: 4 kmh

May 16

7°C / 13°C

clear sky

humidity: 75% | wind: 4 kmh

May 17

7°C / 12°C

clear sky

humidity: 83% | wind: 4 kmh

May 18

7°C / 12°C

clear sky

humidity: 79% | wind: 7 kmh

Local Water Conditions and Nearby Spots

Swimming Conditions

Swimming is allowed at Nine Mile Beach, but it’s best suited to confident and experienced ocean users. This is an exposed stretch of coastline, regularly affected by Tasman Sea swells, shifting sandbars and rip currents. Conditions can change quickly depending on wind direction and offshore weather systems. There are generally no lifeguard patrols, so swimmers need to assess the sea carefully before entering the water. On calm summer days the water can be refreshing, and short swims are possible for those used to cooler temperatures. Outside the warmer months, thermal gear is strongly recommended. Nine Mile offers wide open space and dramatic coastal scenery, but the ocean environment demands caution year-round.