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

57.4

°F

March 12, 19:17

Trend:

stable

Yesterday:

57.2°F

Tomorrow:

57.1°F

Sunrise:

05:55

Sunset:

17:43

Day Length:

11 h. 48 min.

Isumi in March

Minimum:

58.8°F

Average:

62.5°F

Maximum:

66.8°F

Sea water temperature in Isumi today

As of now, in Isumi, the water temperature is 57.4°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 2.4°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 fall 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 is also close to the historical minimum temperature for this date. The maximum temperature recorded for this date was 62.2°F on 2024, while the historical minimum was 58.3°F on 2020.

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 56.8°F, the minimum temperature may reach 56.6°F, and the maximum might stay at 57.1°F.

Daily water temperature in Isumi

Date Current Year

actual* / forecast**

last year 10 years average
Feb 26 58.2°F 59.2°F 59.6°F
Feb 27 57.8°F 59.5°F 58.9°F
Feb 28 57.9°F 58.6°F 58.7°F
Mar 1 57.6°F 59.0°F 59.2°F
Mar 2 57.6°F 59.6°F 59.4°F
Mar 3 58.2°F 59.2°F 59.6°F
Mar 4 60.2°F 59.1°F 59.9°F
Mar 5 58.1°F 59.3°F 59.6°F
Mar 6 58.1°F 59.4°F 59.3°F
Mar 7 60.0°F 59.0°F 59.5°F
Mar 8 59.0°F 58.1°F 59.5°F
Mar 9 57.6°F 61.1°F 59.8°F
Mar 10 59.8°F 60.7°F 59.8°F
Mar 11 57.2°F 60.5°F 59.9°F
Mar 12 57.4°F 59.9°F 59.8°F
Mar 13 57.1°F 60.0°F 59.5°F
Mar 14 56.8°F 60.4°F 59.2°F
Mar 15 56.9°F 59.3°F 59.3°F
Mar 16 56.6°F 59.5°F 59.0°F
Mar 17 56.9°F 58.6°F 59.3°F
Mar 18 56.8°F 57.6°F 59.2°F
Mar 19 56.7°F 58.1°F 59.1°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 58.7°F 8mi
Ichihara 55.0°F 27mi
Kisarazu 54.6°F 29mi
Chiba 55.1°F 30mi
Kimitsu 54.0°F 31mi
Futtsu 54.3°F 34mi
Honchō 53.4°F 40mi
Yokosuka 55.2°F 42mi
Kawasaki 52.5°F 44mi
Yokohama 52.8°F 45mi

* current water temperature in this city

** straight line distance from Isumi