Map from Google - Niigata

In Niigata, a city of Japan, located on the northwest side of Honshu Island, the climate is humid semi-continental, with cold and damp winters, and hot and moist summers, and 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 metres (6 feet and a half) of snow per year fall. 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 metres 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 in 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 for the thermal inertia of the sea, and for the lower frequency of periods of bad weather.
Here are the average temperatures.
Average temperatures - Niigata
NiigataJanFebMarAprMayJunJulAugSepOctNovDec
NiigataJFMAMJJASOND
Min (°C)002713182223191373
Max (°C)661016212428312620149
Min (°F)323236455564727366554537
Max (°F)434350617075828879685748

In Niigata, precipitation is abundant: 1,800 millimetres (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.
Average precipitation - Niigata
NiigataJanFebMarAprMayJunJulAugSepOctNovDecYear
NiigataJFMAMJJASONDY
Prec. (mm)195125120100951251901051751651702651830
Prec. (in)7.74.94.73.93.74.97.54.16.96.56.710.472
Days221917121011131113141824184

In the latter part of summer and in early autumn, from August to October, Niigata may be affected by typhoons, though with less frequency and intensity than in southern Japan.
The cherry blossoming in Niigata occurs around April the 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 never very good, however, there are usually 5/6 hours of sunshine per day, with a peak of 7 hours in August, which as we saw is among the summer months the one with the best weather.
Sunshine - Niigata
NiigataJanFebMarAprMayJunJulAugSepOctNovDec
NiigataJFMAMJJASOND
Sun (hours)234676575532

Niigata

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