Honshu, map

The climate of Kobe, a Japanese city in the southern part of Honshu Island, in the Kansai region, is temperate humid, with quite mild winters and hot, moist, and rainy summers. Like the rest of Japan, the city is affected by the monsoon circulation: in winter, the northwest cold currents will prevail, while in summer, they will be replaced by hot and humid currents of tropical origin.
Kobe is located on the coast, in the Seto Inland Sea, an area relatively protected from both summer monsoon and typhoons. The city is stretched along the coast, with a range of low mountains behind (the Rokko Mountains), while to the east, it is practically merged with Osaka and Kyoto, in a large metropolitan area called Keihanshin.
In winter, there are fairly mild periods, with highs above 10 °C (50 °F), alternating with cold periods, with wind and rain, highs around 5/7 °C (41/45 °F) or less, and possible falls of sleet or snow. Snowfalls, however, are light, as are nocturnal frosts.
Summers are hot and humid; there can be periods of good weather, with maximum temperatures around 35 °C (95 °F) or above, tropical nights and high humidity, but also periods of bad weather due to the summer monsoon. August is the hottest month, both because of the thermal inertia of the sea and because of the lower frequency of periods of bad weather.
Here are the average temperatures.
Kobe - Average temperatures
Min (°C)33611162024262216115
Max (°C)91013192327303228231712
Min (°F)373743526168757972615241
Max (°F)485055667381869082736354

Rainfall is quite abundant, in fact it amounts to 1,200 millimeters (47 inches) per year. Winter is undoubtedly the driest season, at least in quantity; the rainiest months are June and July, ie the first period of the rainy season (called Baiu). In August, there is a certain decrease in rain frequency: on average, among the summer months, it is the hottest as well as the driest and sunniest. Here is the average precipitation.
Kobe - Average precipitation

From June to October (but especially from August to early October), Kobe may be affected by typhoons, the tropical cyclones of Southeast Asia, though this area of the Seto Inland Sea is relatively sheltered (however, in September 1934, the city was hit by a typhoon that caused a lot of damage).
The cherry blossoming in Kobe occurs around April 3rd.
The amount of sunshine in Kobe, all in all, is decent in winter, but it never becomes very good, however, there are two relative maxima, one in spring (April-May) and the other in August, after the Baiu rains. Here are the average sunshine hours per day.
Kobe - Sunshine


The sea in Kobe is warm enough for swimming, with a temperature of 23 °C (73 °F) or more, from July to October, and it becomes pleasantly warm in August. Here are the average sea temperatures.
Kobe - Sea temperature
Temp (°C)171516171922252726232119
Temp (°F)635961636672778179737066