What is the current water temperature in Isumi?

As of now, in Isumi, the water temperature is 23.27°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.

73.9

°F

June 28, 23:18

Trend:

increasing

Yesterday:

73.8°F

Tomorrow:

74.3°F

Sunrise:

04:26

Sunset:

18:57

Day Length:

14 h. 31 min.

Isumi in July

Minimum:

58.8°F

Average:

62.3°F

Maximum:

66.0°F

Sea water temperature in Isumi today

As of now, in Isumi, the water temperature is 73.9°F. It's safe to say that the water is comfortably warm for various water-related activities. Today's reading is 2.8°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 rise a bit.

Recent sea temperature and forecast

Today's water temperature is notably higher than the average recorded over the past two weeks, indicating a significant warming trend. It is also close to the historical maximum temperature for this date. The maximum temperature recorded for this date was 72.3°F on 2018, while the historical minimum was 69.9°F on 2022.

latest data

last year

Observations from the last two weeks indicate that the water temperature was in proximity to the highest values recorded on those days in the past. The forecast for the upcoming week suggests a gradual increase. The average temperature is expected to rise up to 74.6°F, with minimum temperature starting at 74.2°F, while the maximum might reach 75.2°F.

Daily water temperature in Isumi

Date	Current Year actual* / forecast**	last year	10 years average
Jun 14	69.9°F	67.8°F	68.7°F
Jun 15	70.2°F	64.5°F	68.4°F
Jun 16	70.4°F	66.0°F	68.8°F
Jun 17	71.8°F	68.1°F	68.6°F
Jun 18	69.6°F	68.6°F	68.8°F
Jun 19	70.1°F	68.9°F	69.1°F
Jun 20	72.7°F	69.4°F	69.7°F
Jun 21	73.8°F	69.4°F	70.2°F
Jun 22	72.6°F	67.5°F	70.0°F
Jun 23	72.6°F	68.0°F	70.4°F
Jun 24	72.5°F	70.9°F	70.9°F
Jun 25	73.5°F	68.9°F	70.5°F
Jun 26	74.2°F	70.3°F	71.3°F
Jun 27	73.8°F	70.8°F	71.0°F
Jun 28	73.9°F	71.0°F	71.1°F
Jun 29	74.3°F	71.2°F	71.5°F
Jun 30	74.2°F	68.8°F	71.4°F
Jul 1	74.4°F	69.1°F	71.6°F
Jul 2	74.2°F	69.6°F	71.4°F
Jul 3	74.8°F	69.9°F	72.0°F
Jul 4	74.9°F	70.2°F	72.1°F
Jul 5	75.2°F	73.9°F	72.4°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 103 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, 74.1°F in Summer, and 73.9°F in Autumn.

Popular neighboring cities and resorts

City	Water temperature*	Distance**
Katsuura	75.3°F	8mi
Ichihara	78.1°F	27mi
Kisarazu	78.5°F	29mi
Chiba	78.3°F	30mi
Kimitsu	78.4°F	31mi
Futtsu	77.6°F	34mi
Honchō	79.9°F	40mi
Yokosuka	75.8°F	42mi
Kawasaki	78.7°F	44mi
Yokohama	78.2°F	45mi

* current water temperature in this city

** straight line distance from Isumi