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

60.6

°F

January 5, 11:52

Trend:

stable

Yesterday:

60.9°F

Tomorrow:

60.9°F

Sunrise:

06:48

Sunset:

16:40

Day Length:

9 h. 52 min.

Isumi in January

Minimum:

57.6°F

Average:

63.1°F

Maximum:

66.3°F

Sea water temperature in Isumi today

As of now, in Isumi, the water temperature is 60.6°F. Swimming in water of this temperature is considered as extremely cold, and there's a substantial risk of hypothermia if exposed for more than a brief duration. Today's reading is 1.4°F lower 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 rise a bit.

Recent sea temperature and forecast

Today's water temperature is considerably lower than the average registered over the last two weeks, indicating a slight cooling trend. It also falls within the range of the average temperature recorded for this date, suggesting a consistent weather trend. The maximum temperature recorded for this date was 66.3°F on 2020, while the historical minimum was 56.8°F on 2022.

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 maximum recorded over the past years. Over the next week, the forecast shows a steady trend, with temperatures staying close to the average of 60.9°F. Both minimum and maximum temperatures expected to be close to the average, offering a week of stable water conditions.

Daily water temperature in Isumi

Date Current Year

actual* / forecast**

last year 10 years average
Jan 1 63.3°F 62.5°F 63.1°F
Jan 2 63.7°F 61.3°F 63.1°F
Jan 3 60.7°F 60.7°F 62.5°F
Jan 4 60.9°F 60.2°F 62.3°F
Jan 5 60.6°F 60.4°F 62.0°F
Jan 6 60.9°F 59.7°F 62.3°F
Jan 7 61.0°F 63.2°F 62.4°F
Jan 8 60.9°F 62.3°F 62.3°F
Jan 9 61.0°F 61.7°F 62.4°F
Jan 10 61.0°F 61.4°F 62.4°F
Jan 11 60.9°F 61.7°F 62.3°F
Jan 12 60.4°F 63.9°F 61.7°F
Dec 22 65.5°F 63.4°F 64.2°F
Dec 23 65.9°F 60.6°F 63.8°F
Dec 24 65.4°F 63.1°F 63.6°F
Dec 25 65.2°F 65.2°F 63.2°F
Dec 26 64.8°F 65.2°F 63.9°F
Dec 27 65.1°F 64.3°F 64.1°F
Dec 28 66.5°F 63.9°F 64.1°F
Dec 29 67.2°F 63.5°F 63.9°F
Dec 30 64.4°F 62.9°F 63.3°F
Dec 31 63.1°F 62.4°F 63.1°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, 74.2°F in Summer, and 74.0°F in Autumn.

Popular neighboring cities and resorts

City Water temperature* Distance**
Katsuura 63.9°F 8mi
Ichihara 53.5°F 27mi
Kisarazu 55.7°F 29mi
Chiba 52.9°F 30mi
Kimitsu 55.6°F 31mi
Futtsu 56.8°F 34mi
Honchō 51.3°F 40mi
Yokosuka 59.5°F 42mi
Kawasaki 53.4°F 44mi
Yokohama 55.7°F 45mi

* current water temperature in this city

** straight line distance from Isumi