Isumi in December
Find out everything about the water temperature in Isumi in December. Average, minimum and maximum recorded temperatures as well as daily temperature in December for the last two years. Compare the current month's sea temperature data with other months of the year.
Water temperature in December
Minimum:
59.4 °F
Average:
65.1 °F
Maximum:
70.4 °F
Sea water temperature in Isumi in December
In the city of Isumi, the month of December is somewhat too cool for swimming. The minimum recorded temperature during this month was 59.4°F on December 25, 2022, with an average temperature being 65.1°F and a maximum temperature reaching 70.4°F on December 1, 2025.
| Date | 10 years average | 2025 | 2024 |
|---|---|---|---|
| Dec 1 | 67.7°F | 70.4°F | 67.0°F |
| Dec 2 | 67.2°F | 69.3°F | 67.0°F |
| Dec 3 | 67.0°F | 69.2°F | 66.3°F |
| Dec 4 | 67.0°F | 66.0°F | 66.7°F |
| Dec 5 | 66.2°F | 65.0°F | 65.8°F |
| Dec 6 | 66.2°F | 65.3°F | 66.8°F |
| Dec 7 | 66.1°F | 66.4°F | 66.9°F |
| Dec 8 | 66.3°F | 68.5°F | 67.4°F |
| Dec 9 | 66.0°F | 69.0°F | 64.3°F |
| Dec 10 | 66.2°F | 68.7°F | 65.6°F |
| Dec 11 | 66.4°F | 68.2°F | 65.2°F |
| Dec 12 | 65.6°F | 67.4°F | 63.8°F |
| Dec 13 | 65.8°F | 66.3°F | 65.5°F |
| Dec 14 | 65.1°F | 66.2°F | 64.8°F |
| Dec 15 | 64.7°F | 64.0°F | 64.3°F |
| Dec 16 | 65.4°F | 67.2°F | 65.8°F |
| Dec 17 | 64.8°F | 67.6°F | 64.9°F |
| Dec 18 | 64.5°F | 68.1°F | 64.8°F |
| Dec 19 | 64.5°F | 68.0°F | 64.3°F |
| Dec 20 | 64.2°F | 65.8°F | 63.1°F |
| Dec 21 | 64.3°F | 65.6°F | 63.5°F |
| Dec 22 | 64.2°F | 65.5°F | 63.4°F |
| Dec 23 | 63.8°F | 65.9°F | 60.6°F |
| Dec 24 | 63.6°F | 65.4°F | 63.1°F |
| Dec 25 | 63.2°F | 65.2°F | 65.2°F |
| Dec 26 | 63.9°F | 64.8°F | 65.2°F |
| Dec 27 | 64.1°F | 65.1°F | 64.3°F |
| Dec 28 | 64.1°F | 66.5°F | 63.9°F |
| Dec 29 | 63.9°F | 67.2°F | 63.5°F |
| Dec 30 | 63.3°F | 64.4°F | 62.9°F |
| Dec 31 | 63.1°F | 63.1°F | 62.4°F |
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.
December's average temperature is a slight drop from November's average of 69.7°F. In January, the temperature is expected to decrease further, potentially averaging around 61.5°F.
Popular neighboring cities and resorts
| City | Water temperature* | Distance** |
|---|---|---|
| Katsuura |
61.1°F
|
8mi |
| Ichihara |
53.2°F
|
27mi |
| Kisarazu |
54.8°F
|
29mi |
| Chiba |
52.6°F
|
30mi |
| Kimitsu |
54.8°F
|
31mi |
| Futtsu |
55.5°F
|
34mi |
| Honchō |
50.1°F
|
40mi |
| Yokosuka |
57.8°F
|
42mi |
| Kawasaki |
53.5°F
|
44mi |
| Yokohama |
55.0°F
|
45mi |
* current water temperature in this city
** straight line distance from Isumi