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Stewart Island Sea Temperature in September

New Zealand

August Stewart Island year-round → October

Average sea temperature for Stewart Island, New Zealand across September, based on 10 years of daily readings.

Average

11.37° C

High

12.47° C

Low

10.12° C

Water at this temperature is cold and will feel very cold initially, but the body will get used to it and longer swims are possible. Experienced swimmers can manage several hours of swimming, however hypothermia is still a real risk.

September is the 12th warmest of 12 months at Stewart Island. On average the water sits 1.3° than the year-round mean of 12.68° C.

Compared to August, September is 0.0° about the same as (11.39° C in August). By October the water is usually 11.57° C.

Stewart Island Day-by-Day Water Temperature in September

10-year low, average and high

9.5° C
10.4° C
11.3° C
12.1° C
13.0° C
1
5
10
15
20
25
30
Day-by-day low and high band with the 10-year daily average through September. Range Average

Each vertical bar above is one day of September. The shaded band covers the range the water has reached on that day across the last 10 years — the lowest reading at the bottom, the highest at the top. The line running through the bars is the daily average over those 10 years, so you can see the typical shape of the month at Stewart Island.

A narrow band means the temperature on that day has stayed close to the average year on year. A taller band means it has swung more, often because of changeable weather around that time of year. Hovering a day pulls up its low, average, and high.

September Water Temperature Table for Stewart Island

10-year daily averages

Day Average Low High
September 1 11.34° C 10.29° C 11.95° C
September 2 11.37° C 10.34° C 11.95° C
September 3 11.41° C 10.43° C 11.96° C
September 4 11.46° C 10.52° C 11.91° C
September 5 11.45° C 10.34° C 11.85° C
September 6 11.43° C 10.16° C 12.01° C
September 7 11.39° C 10.12° C 12.31° C
September 8 11.43° C 10.66° C 12.31° C
September 9 11.4° C 10.73° C 12.03° C
September 10 11.41° C 10.71° C 11.84° C
September 11 11.37° C 10.58° C 11.76° C
September 12 11.38° C 10.62° C 11.82° C
September 13 11.34° C 10.61° C 11.86° C
September 14 11.34° C 10.62° C 11.71° C
September 15 11.32° C 10.58° C 11.68° C
September 16 11.26° C 10.38° C 11.64° C
September 17 11.33° C 10.41° C 11.84° C
September 18 11.37° C 10.5° C 11.91° C
September 19 11.38° C 10.62° C 11.85° C
September 20 11.36° C 10.77° C 11.71° C
September 21 11.35° C 10.82° C 11.66° C
September 22 11.32° C 10.72° C 11.73° C
September 23 11.32° C 10.7° C 11.8° C
September 24 11.31° C 10.67° C 11.83° C
September 25 11.29° C 10.66° C 11.84° C
September 26 11.36° C 10.61° C 12.28° C
September 27 11.39° C 10.64° C 12.31° C
September 28 11.43° C 10.71° C 12.47° C
September 29 11.39° C 10.65° C 12.25° C
September 30 11.36° C 10.64° C 12.04° C

Where September Sits in the Year

September highlighted

9.0° C
11.4° C
13.8° C
16.1° C
18.5° C
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
13.88° C
14.16° C
14° C
13.57° C
12.96° C
12.07° C
11.5° C
11.39° C
11.37° C
11.57° C
12.36° C
13.27° C
10-year monthly history for Stewart Island. Bars span historical low to high; the line marks the monthly average. Range Average
January → February → March → April → May → June → July → August → September → October → November → December →

Nearby Locations in September

Compare other New Zealand water for the same month

Stewart Island Location

-47.0103, 167.8272

-47.01032, 167.82723 View on OpenStreetMap →

Stewart Island sits at -47.0103°N, 167.8272°E, on the coast of New Zealand. The marker on the map shows the spot the readings on this page come from. It usually sits a short distance from the town centre, out on the open water itself, so the numbers stay tied to the coast rather than a generic point inland.

Coastlines bend, headlands focus the water, and the temperature can run noticeably differently between two beaches that look close together on a map. Comparing nearby locations is a quick way to see how local geography is shaping the readings.

Nearest locations to Stewart Island