What is the current water temperature in Isumi?

As of now, in Isumi, the water temperature is 25.85°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.

78.5

°F

September 17, 14:22

Trend:

stable

Yesterday:

78.4°F

Tomorrow:

78.3°F

Sunrise:

05:22

Sunset:

17:44

Day Length:

12 h. 22 min.

Isumi in September

Minimum:

59.8°F

Average:

62.4°F

Maximum:

64.9°F

Sea water temperature in Isumi today

As of now, in Isumi, the water temperature is 78.5°F. It's safe to say that the water is comfortably warm for various water-related activities. Today's reading is 0.4°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 fall 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 81.0°F on 2024, while the historical minimum was 75.5°F on 2021.

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 maximum recorded over the past years. The forecast for the upcoming week shows a gradual cooling trend. The average temperature is expected to be 77.8°F, the minimum temperature may reach 77.3°F, and the maximum might stay at 78.3°F.

Daily water temperature in Isumi

Date	Current Year actual* / forecast**	last year	10 years average
Sep 3	80.4°F	78.7°F	78.6°F
Sep 4	79.9°F	77.1°F	78.4°F
Sep 5	79.6°F	77.5°F	78.3°F
Sep 6	77.3°F	76.6°F	78.2°F
Sep 7	78.1°F	77.6°F	78.6°F
Sep 8	77.9°F	77.7°F	78.5°F
Sep 9	77.8°F	77.7°F	78.2°F
Sep 10	78.0°F	79.4°F	78.2°F
Sep 11	78.9°F	80.2°F	78.4°F
Sep 12	79.0°F	79.3°F	78.4°F
Sep 13	79.8°F	79.1°F	78.3°F
Sep 14	78.6°F	79.1°F	78.4°F
Sep 15	78.0°F	78.7°F	78.1°F
Sep 16	78.4°F	78.3°F	78.0°F
Sep 17	78.5°F	81.0°F	78.1°F
Sep 18	78.3°F	80.2°F	77.8°F
Sep 19	78.1°F	79.3°F	77.7°F
Sep 20	78.2°F	81.2°F	77.8°F
Sep 21	78.0°F	80.4°F	77.6°F
Sep 22	77.5°F	80.0°F	77.1°F
Sep 23	77.3°F	78.5°F	76.9°F
Sep 24	77.4°F	78.0°F	76.9°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, 74.2°F in Summer, and 73.9°F in Autumn.

Popular neighboring cities and resorts

City	Water temperature*	Distance**
Katsuura	77.8°F	8mi
Ichihara	82.5°F	27mi
Kisarazu	80.5°F	29mi
Chiba	82.5°F	30mi
Kimitsu	80.2°F	31mi
Futtsu	79.2°F	34mi
Honchō	82.1°F	40mi
Yokosuka	78.5°F	42mi
Kawasaki	81.4°F	44mi
Yokohama	80.5°F	45mi

* current water temperature in this city

** straight line distance from Isumi