What is the current water temperature in Isumi?

As of now, in Isumi, the water temperature is 26.27°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.

79.3

°F

September 1, 13:45

Trend:

decreasing

Yesterday:

79.6°F

Tomorrow:

79.1°F

Sunrise:

05:10

Sunset:

18:06

Day Length:

12 h. 56 min.

Isumi in September

Minimum:

59.8°F

Average:

62.5°F

Maximum:

64.9°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

Today's water temperature is considerably 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 80.5°F on 2020, while the historical minimum was 76.0°F on 2019.

latest data

last year

Over the last two weeks, the water temperature has stayed slightly above than historical averages for those days. Over the next week, the forecast shows a steady trend, with temperatures staying close to the average of 79.0°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 18	79.6°F	78.1°F	78.7°F
Aug 19	80.3°F	77.6°F	78.6°F
Aug 20	80.2°F	76.0°F	78.6°F
Aug 21	80.4°F	78.2°F	78.8°F
Aug 22	80.6°F	77.4°F	78.7°F
Aug 23	81.3°F	79.6°F	79.3°F
Aug 24	82.5°F	78.6°F	79.1°F
Aug 25	80.7°F	78.1°F	78.5°F
Aug 26	79.8°F	79.0°F	79.2°F
Aug 27	78.4°F	76.6°F	79.3°F
Aug 28	80.8°F	77.0°F	79.5°F
Aug 29	79.8°F	77.3°F	79.4°F
Aug 30	80.0°F	77.5°F	79.0°F
Aug 31	79.6°F	78.5°F	79.1°F
Sep 1	79.3°F	79.9°F	78.7°F
Sep 2	79.1°F	78.8°F	78.5°F
Sep 3	79.1°F	80.4°F	78.5°F
Sep 4	78.9°F	79.9°F	78.3°F
Sep 5	78.9°F	79.6°F	78.3°F
Sep 6	78.8°F	77.3°F	78.2°F
Sep 7	79.3°F	78.1°F	78.7°F
Sep 8	79.1°F	77.9°F	78.5°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	80.5°F	8mi
Ichihara	82.8°F	27mi
Kisarazu	82.5°F	29mi
Chiba	82.6°F	30mi
Kimitsu	82.3°F	31mi
Futtsu	81.7°F	34mi
Honchō	82.4°F	40mi
Yokosuka	80.5°F	42mi
Kawasaki	81.6°F	44mi
Yokohama	81.0°F	45mi

* current water temperature in this city

** straight line distance from Isumi