Honshu, map

In Niigata, a city of Japan, located on the northwest side of Honshu Island, the climate is humid semi-continental, with cold, damp winters and hot, moist summers; in addition, there is no dry season. Like the rest of Japan, the city is affected by the monsoon circulation: in winter the northwest cold currents prevail, while in summer they are replaced by hot and humid currents of tropical origin.
In winter, cold winds from the Asian continent are loaded with moisture across the sea, and hit the coast directly: in Niigata, the temperature is slightly above freezing (0 °C or 32 °F), the sky is cloudy, the wind blows, and it rains and snows almost every day. On average, more than two meters (6 feet and a half) of snow fall per year. Waves of intense cold are rare: generally the temperature does not drop below -5 °C (23 °F), although the cold is fairly constant and the air is humid.
While the presence of maritime air in the city makes great snowfalls rare, in the interior regions, already at low altitude but especially on the slopes of the mountains exposed to the northwest, very heavy snowfalls occur, and meters of snow accumulate: it is no coincidence that this region of Japan is called "snow country", Yukiguni (and in the mountains there are several ski lifts). It snows a lot also on the neighboring island of Sado, at least in inland mountainous areas.
In summer, periods of fine weather, hot and humid, alternate with periods of bad weather, with wind and rain, and sometimes (especially in June) a little cool at night. August is the warmest 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.
Niigata - Average temperatures
Min (°C)002713182223191373
Max (°C)661016212428312620149
Min (°F)323236455564727366554537
Max (°F)434350617075828879685748

In Niigata, precipitation is abundant: 1,800 millimeters (70 inches) per year. The (relatively) driest season is spring; in summer, when the monsoon is somewhat less intense than in southern Japan, in August there is a certain drop in rainfall. Here is the average precipitation.
Niigata - Average precipitation

From June to October (but especially from August to early October), Niigata may be affected by typhoons, though typically with less frequency and intensity than in southern Japan.
The cherry blossoming in Niigata occurs around April 13th, with a variability of about one week before or after depending on the year.
The sun in Niigata is rarely seen in winter, when the sky is generally cloudy; in the other seasons, the degree of sunshine is not very good, however, there are usually 5/6 hours of sunshine per day, with a peak of 7 hours in August, which as we said is among the summer months the one with the best weather.
Niigata - Sunshine


In Niigata, the sea becomes warm enough for swimming in August and September, while it is a bit cool in July.
Niigata - Sea temperature
Temp (°C)1188101317212423201713
Temp (°F)524646505563707573686355