All data are in degrees Fahrenheit

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Water temperature in Isumi

Detailed information about the current water temperature in Isumi. The trend over the last two weeks, daily averages, and precise forecast of the water temperature changes. Gain a deeper understanding of seasonal dynamics with monthly statistical analyses covering recent years.
Sea temperature in Isumi now

76.4

°F

September 29, 16:37

Trend:

stable

Yesterday:

76.2°F

Tomorrow:

76.3°F

Sunrise:

05:31

Sunset:

17:26

Day Length:

11 h. 55 min.

Isumi in October

Minimum:

59.8°F

Average:

62.5°F

Maximum:

65.4°F

Sea water temperature in Isumi today

As of now, in Isumi, the water temperature is 76.4°F. It's safe to say that the water is comfortably warm for various water-related activities. Today's reading is 0.6°F lower than the average recorded on this particular day in recent years. Since yesterday, there was a slight increase in temperature. This indicates a warming trend over the past day. According to the forecast, we expect the temperature to stay about the same.

Recent sea temperature and forecast

The water temperature today is above average for the last two weeks, showing a small increase in temperature. It is also close to the historical minimum temperature for this date. The maximum temperature recorded for this date was 78.2°F on 2017, while the historical minimum was 75.8°F on 2021.

The water temperature over the last two weeks displayed soome variability. While the two week average stayed close to the historical average, there were some days when the temperature was close to the minimum recorded over the past years. The forecast for the upcoming week shows a gradual cooling trend. The average temperature is expected to be 75.2°F, the minimum temperature may reach 74.7°F, and the maximum might stay at 76.3°F.

Daily water temperature in Isumi

Date Current Year

actual* / forecast**

last year 10 years average
Sep 15 77.0°F 78.0°F 78.1°F
Sep 16 76.8°F 78.4°F 78.0°F
Sep 17 77.5°F 79.3°F 78.3°F
Sep 18 73.5°F 79.7°F 77.8°F
Sep 19 74.1°F 79.1°F 77.6°F
Sep 20 74.5°F 79.1°F 77.7°F
Sep 21 75.8°F 78.6°F 77.6°F
Sep 22 76.2°F 77.1°F 77.0°F
Sep 23 76.2°F 77.0°F 76.9°F
Sep 24 75.8°F 77.3°F 76.9°F
Sep 25 75.3°F 76.4°F 76.6°F
Sep 26 76.3°F 76.2°F 76.8°F
Sep 27 76.2°F 76.8°F 77.0°F
Sep 28 76.2°F 77.8°F 76.9°F
Sep 29 76.4°F 77.8°F 77.1°F
Sep 30 76.3°F 76.4°F 76.9°F
Oct 1 75.5°F 75.3°F 76.1°F
Oct 2 75.0°F 75.6°F 75.7°F
Oct 3 74.9°F 75.3°F 75.6°F
Oct 4 75.2°F 75.3°F 75.8°F
Oct 5 74.7°F 75.5°F 75.4°F
Oct 6 75.1°F 76.3°F 75.7°F

* actual - actual temperature values

** forecast - projected values for the next week

Real-time coastal temperatures could deviate by several degrees from the provided readings. These deviations often become evident following intense rainfall or strong winds.

Our forecasting methodology leverages a mathematical model, that uses current water and weather conditions, historical records, wind intensity and direction.

Sea water temperature in Isumi by month

In Isumi, the months July through October offer comfortable swimming conditions, which amounts to 109 swimming days.
The warmest water in Isumi was recorded on August 17, 2024, reaching a 82.8°F. While the coldest temperature occurred on April 20, 2025, dipping to 53.1°F. The average readings by season are 62.1°F in Winter, 61.8°F in Spring, 74.3°F in Summer, and 74.0°F in Autumn.

Popular neighboring cities and resorts

City Water temperature* Distance**
Katsuura 77.3°F 8mi
Ichihara 74.0°F 27mi
Kisarazu 73.8°F 29mi
Chiba 73.6°F 30mi
Kimitsu 73.8°F 31mi
Futtsu 73.7°F 34mi
Honchō 73.1°F 40mi
Yokosuka 74.2°F 42mi
Kawasaki 74.0°F 44mi
Yokohama 74.0°F 45mi

* current water temperature in this city

** straight line distance from Isumi