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

78.3

°F

July 16, 09:46

Trend:

increasing

Yesterday:

78.2°F

Tomorrow:

78.3°F

Sunrise:

04:35

Sunset:

18:53

Day Length:

14 h. 18 min.

Isumi in July

Minimum:

58.8°F

Average:

62.3°F

Maximum:

66.0°F

Sea water temperature in Isumi today

As of now, in Isumi, the water temperature is 78.3°F. It's safe to say that the water is comfortably warm for various water-related activities. Today's reading is 3.8°F higher than the average recorded on this particular day in recent years. The sea temperature remains approximately unchanged from yesterday. According to the forecast, we expect the temperature to stay about the same.

Recent sea temperature and forecast

Today's water temperature is notably higher than the average recorded over the past two weeks, indicating a significant warming trend. It is also close to the historical maximum temperature for this date. The maximum temperature recorded for this date was 76.9°F on 2018, while the historical minimum was 71.7°F on 2019.

Observations from the last two weeks indicate that the water temperature was in proximity to the highest values recorded on those days in the past. The forecast for the upcoming week suggests a gradual increase. The average temperature is expected to rise up to 78.8°F, with minimum temperature starting at 78.3°F, while the maximum might reach 79.5°F.

Daily water temperature in Isumi

Date Current Year

actual* / forecast**

last year 10 years average
Jul 2 74.6°F 69.6°F 71.7°F
Jul 3 72.9°F 69.9°F 72.1°F
Jul 4 73.8°F 70.2°F 72.2°F
Jul 5 72.5°F 73.9°F 72.4°F
Jul 6 73.3°F 74.1°F 72.8°F
Jul 7 77.0°F 74.1°F 73.1°F
Jul 8 76.0°F 73.9°F 73.4°F
Jul 9 77.1°F 74.6°F 73.6°F
Jul 10 76.9°F 74.9°F 73.3°F
Jul 11 77.1°F 75.0°F 73.7°F
Jul 12 77.5°F 75.0°F 73.9°F
Jul 13 79.9°F 75.1°F 74.3°F
Jul 14 79.1°F 75.0°F 74.6°F
Jul 15 78.2°F 73.8°F 74.4°F
Jul 16 78.3°F 73.9°F 74.5°F
Jul 17 78.3°F 74.1°F 74.5°F
Jul 18 78.4°F 74.0°F 74.6°F
Jul 19 78.5°F 75.4°F 74.7°F
Jul 20 78.8°F 74.9°F 75.0°F
Jul 21 79.0°F 75.1°F 75.2°F
Jul 22 79.5°F 77.1°F 75.7°F
Jul 23 79.2°F 77.5°F 75.4°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 105 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, 61.9°F in Spring, 74.1°F in Summer, and 73.9°F in Autumn.

Popular neighboring cities and resorts

City Water temperature* Distance**
Katsuura 80.0°F 8mi
Ichihara 80.7°F 27mi
Kisarazu 78.9°F 29mi
Chiba 80.9°F 30mi
Kimitsu 78.6°F 31mi
Futtsu 77.7°F 34mi
Honchō 81.4°F 40mi
Yokosuka 77.0°F 42mi
Kawasaki 80.5°F 44mi
Yokohama 79.4°F 45mi

* current water temperature in this city

** straight line distance from Isumi