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 18.9°C. Swimming in water of this temperature is generally concidered to be cool, and most people won't really enjoy it.

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.

66.0

°F

May 25, 21:34

Trend:

decreasing

Yesterday:

67.0°F

Tomorrow:

66.0°F

Sunrise:

04:28

Sunset:

18:42

Day Length:

14 h. 14 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 66.0°F. Swimming in water of this temperature is generally concidered to be cool, and most people won't really enjoy it. Today's reading is 0.7°F lower 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

Today's water temperature closely matches the previous two weeks' average, indicating a stable 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 69.7°F on 2021, while the historical minimum was 65.0°F on 2022.

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. The forecast for the upcoming week suggests a gradual increase. The average temperature is expected to rise up to 66.8°F, with minimum temperature starting at 66.0°F, while the maximum might reach 67.4°F.

Daily water temperature in Isumi

Date	Current Year actual* / forecast**	last year	10 years average
May 11	62.5°F	64.0°F	64.4°F
May 12	60.3°F	63.4°F	63.8°F
May 13	62.5°F	63.4°F	63.8°F
May 14	63.6°F	62.9°F	63.8°F
May 15	64.5°F	64.1°F	64.3°F
May 16	65.9°F	64.6°F	64.7°F
May 17	67.1°F	64.9°F	64.8°F
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	66.0°F	66.3°F	66.7°F
May 27	66.3°F	66.5°F	67.0°F
May 28	66.6°F	67.0°F	67.3°F
May 29	67.1°F	67.6°F	67.9°F
May 30	66.9°F	67.6°F	67.6°F
May 31	67.3°F	68.0°F	68.0°F
Jun 1	67.4°F	69.2°F	68.1°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	66.3°F	8mi
Ichihara	67.8°F	27mi
Kisarazu	65.2°F	29mi
Chiba	68.6°F	30mi
Kimitsu	65.3°F	31mi
Futtsu	65.3°F	34mi
Honchō	68.3°F	40mi
Yokosuka	67.6°F	42mi
Kawasaki	69.2°F	44mi
Yokohama	68.9°F	45mi

* current water temperature in this city

** straight line distance from Isumi