What is the current water temperature in Isumi?

As of now, in Isumi, the water temperature is 25.49°C. It's safe to say that the water is comfortably warm for various water-related activities.

Japan > Isumi

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.

77.9

°F

August 11, 12:31

Trend:

increasing

Yesterday:

77.7°F

Tomorrow:

78.0°F

Sunrise:

04:54

Sunset:

18:33

Day Length:

13 h. 39 min.

Isumi in August

Minimum:

58.6°F

Average:

62.3°F

Maximum:

65.4°F

Sea water temperature in Isumi today

As of now, in Isumi, the water temperature is 77.9°F. It's safe to say that the water is comfortably warm for various water-related activities. Today's reading is 0.7°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 rise a bit.

Recent sea temperature and forecast

Today's water temperature is slightly 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 80.3°F on 2016, while the historical minimum was 76.4°F on 2023.

latest data

last year

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 histoorical minimum and others when it was close to the historical maximum. The forecast for the upcoming week suggests a gradual increase. The average temperature is expected to rise up to 78.2°F, with minimum temperature starting at 77.9°F, while the maximum might reach 78.7°F.

Daily water temperature in Isumi

Date	Current Year actual* / forecast**	last year	10 years average
Jul 28	77.6°F	77.3°F	76.4°F
Jul 29	79.8°F	79.0°F	76.8°F
Jul 30	78.3°F	77.1°F	76.9°F
Jul 31	78.7°F	79.7°F	77.1°F
Aug 1	77.6°F	80.3°F	77.1°F
Aug 2	79.2°F	81.4°F	77.7°F
Aug 3	77.9°F	79.0°F	77.7°F
Aug 4	77.4°F	79.9°F	78.0°F
Aug 5	78.3°F	78.2°F	78.2°F
Aug 6	73.4°F	80.1°F	78.2°F
Aug 7	78.7°F	80.6°F	79.2°F
Aug 8	79.5°F	80.9°F	79.2°F
Aug 9	78.8°F	80.8°F	79.1°F
Aug 10	77.7°F	80.1°F	78.4°F
Aug 11	77.9°F	80.2°F	78.6°F
Aug 12	78.0°F	79.0°F	78.7°F
Aug 13	78.4°F	79.2°F	79.1°F
Aug 14	78.7°F	79.9°F	79.4°F
Aug 15	78.1°F	75.3°F	78.8°F
Aug 16	78.4°F	75.9°F	79.1°F
Aug 17	78.1°F	76.4°F	78.8°F
Aug 18	77.9°F	78.1°F	78.6°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	79.7°F	8mi
Ichihara	81.1°F	27mi
Kisarazu	80.9°F	29mi
Chiba	81.4°F	30mi
Kimitsu	80.7°F	31mi
Futtsu	80.5°F	34mi
Honchō	84.3°F	40mi
Yokosuka	80.6°F	42mi
Kawasaki	82.8°F	44mi
Yokohama	82.7°F	45mi

* current water temperature in this city

** straight line distance from Isumi