What is the current water temperature in Isumi?

Q: What is the current water temperature in Isumi?

As of now, in Isumi, the water temperature is 20.4°C. Swimming in water of this temperature is seen as relatively warm and enjoyable for some individuals, although many might find it slightly too cool.

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.

68.7

°F

June 1, 22:09

Trend:

decreasing

Yesterday:

68.9°F

Tomorrow:

68.7°F

Sunrise:

04:25

Sunset:

18:47

Day Length:

14 h. 22 min.

Isumi in June

Minimum:

58.6°F

Average:

62.1°F

Maximum:

65.8°F

Sea water temperature in Isumi today

As of now, in Isumi, the water temperature is 68.7°F. Swimming in water of this temperature is seen as relatively warm and enjoyable for some individuals, although many might find it slightly too cool. 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 stay about the same.

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 70.3°F on 2016, while the historical minimum was 63.2°F on 2021.

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. Over the next week, the forecast shows a steady trend, with temperatures staying close to the average of 68.7°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
May 18	68.3°F	65.4°F	65.1°F
May 19	69.5°F	65.6°F	65.6°F
May 20	67.5°F	63.2°F	65.4°F
May 21	68.0°F	65.9°F	65.9°F
May 22	68.1°F	65.9°F	66.2°F
May 23	67.5°F	66.1°F	66.5°F
May 24	67.0°F	66.1°F	66.8°F
May 25	66.0°F	66.2°F	66.7°F
May 26	67.3°F	66.3°F	66.8°F
May 27	69.2°F	66.5°F	67.2°F
May 28	69.2°F	67.0°F	67.5°F
May 29	70.1°F	67.6°F	68.1°F
May 30	71.1°F	67.6°F	67.9°F
May 31	68.9°F	68.0°F	68.1°F
Jun 1	68.7°F	69.2°F	68.1°F
Jun 2	68.7°F	68.4°F	68.0°F
Jun 3	68.5°F	68.6°F	67.9°F
Jun 4	68.3°F	67.4°F	67.6°F
Jun 5	68.7°F	67.4°F	68.1°F
Jun 6	68.8°F	67.7°F	68.2°F
Jun 7	69.0°F	69.2°F	68.3°F
Jun 8	69.0°F	69.4°F	68.3°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, 74.2°F in Summer, and 74.0°F in Autumn.

Popular neighboring cities and resorts

City	Water temperature*	Distance**
Katsuura	72.3°F	8mi
Ichihara	73.1°F	27mi
Kisarazu	72.4°F	29mi
Chiba	73.0°F	30mi
Kimitsu	71.6°F	31mi
Futtsu	70.4°F	34mi
Honchō	73.0°F	40mi
Yokosuka	69.0°F	42mi
Kawasaki	71.9°F	44mi
Yokohama	71.1°F	45mi

* current water temperature in this city

** straight line distance from Isumi