What is the current water temperature in Isumi?

As of now, in Isumi, the water temperature is 26.25°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.

79.3

°F

August 18, 12:47

Trend:

decreasing

Yesterday:

79.5°F

Tomorrow:

79.1°F

Sunrise:

05:00

Sunset:

18:25

Day Length:

13 h. 25 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 79.3°F. It's safe to say that the water is comfortably warm for various water-related activities. Today's reading is 0.6°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

The water temperature today is above average for the last two weeks, showing a small increase in temperature. 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 82.1°F on 2024, while the historical minimum was 76.8°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 histoorical minimum and others when it was close to the historical maximum. Over the next week, the forecast shows a steady trend, with temperatures staying close to the average of 79.2°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
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	80.0°F	78.3°F
Aug 11	79.8°F	80.4°F	78.7°F
Aug 12	80.2°F	79.0°F	78.9°F
Aug 13	79.2°F	79.2°F	79.1°F
Aug 14	80.3°F	79.9°F	79.5°F
Aug 15	80.1°F	75.3°F	79.0°F
Aug 16	80.2°F	75.9°F	79.2°F
Aug 17	79.5°F	76.4°F	78.8°F
Aug 18	79.3°F	78.1°F	78.6°F
Aug 19	79.1°F	77.6°F	78.5°F
Aug 20	79.1°F	76.0°F	78.5°F
Aug 21	79.3°F	78.2°F	78.7°F
Aug 22	79.1°F	77.4°F	78.5°F
Aug 23	79.7°F	79.6°F	79.1°F
Aug 24	79.4°F	78.6°F	78.7°F
Aug 25	78.9°F	78.1°F	78.2°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	80.0°F	8mi
Ichihara	77.0°F	27mi
Kisarazu	77.1°F	29mi
Chiba	77.6°F	30mi
Kimitsu	77.0°F	31mi
Futtsu	77.2°F	34mi
Honchō	77.4°F	40mi
Yokosuka	77.5°F	42mi
Kawasaki	77.8°F	44mi
Yokohama	78.4°F	45mi

* current water temperature in this city

** straight line distance from Isumi