Japan Weekly Weather Forecast: Heavy Rain and Thunderstorms Expected Across Regions

Japan is facing a volatile weather pattern through April 12, 2026, characterized by a sequence of passing low-pressure systems and fronts that will bring a mix of summer-like warmth and severe precipitation across the archipelago.

According to reports from Sunny Spot and Weather News, the current meteorological trend involves low-pressure systems and fronts passing periodically near Japan, leading to deteriorating conditions over wide areas.

Immediate Forecast and Temperature Trends

On April 7, 2026, low-pressure systems moved east-northeast around the southern coast of Honshu and Hokkaido, resulting in rain across many parts of the country. In the Hokuriku region and northern Japan, snow fell in several locations, primarily along mountain ranges, due to the influence of cold air in the upper atmosphere.

Conditions are expected to improve on April 8, 2026, as a high-pressure system emerges from the west and covers the Honshu region, bringing sunny weather to many areas. However, northern Japan may experience increased winds due to a large atmospheric pressure gradient between the high pressure over Honshu and a low-pressure system situated near the Sea of Okhotsk.

While some regions have seen temperatures fail to rise significantly, with maximum temperatures often recorded during morning observations, warmer conditions are anticipated for the major metropolitan areas of Tokyo, Nagoya, and Osaka, where summer-like days are forecasted.

Severe Weather Warnings for April 9 and 10

The weather is expected to deteriorate again starting April 9, 2026. A low-pressure system accompanied by a front is projected to move eastward from the vicinity of the Yellow Sea, bringing rain to western Japan in the afternoon. Reports from BSN Niigata Broadcasting and TBS News Dig indicate that this system may bring intense rain accompanied by thunder in western Japan.

The situation is expected to intensify on April 10, 2026. A developing low-pressure system will move toward the Sea of Japan and continue to strengthen as it progresses northeast. This system is expected to bring rain over a wide area of Japan as the associated front passes.

Weather News has cautioned that the atmosphere on April 10 may feature warm, moist air currents similar to those seen during the rainy season, increasing the risk of heavy rainfall. There are concerns that the combination of low pressure and winds blowing toward the front could trigger torrential rain and thunderstorms across both western and eastern Japan.

Outlook for April 11 and 12

By Saturday, April 11, 2026, weather conditions are expected to improve in eastern and western Japan. However, instability will persist in northern Japan and the Hokuriku region, where rain is likely to continue.

The Hokkaido region is expected to face particularly challenging conditions on April 11. Due to the proximity of a low-pressure system, strong winds are forecasted to persist in the area. TBS News Dig and BSN Niigata Broadcasting have warned of the possibility of severe weather and turbulent conditions centering on northern Japan during this period.

Residents and travelers are advised to monitor the latest updates from the Japan Meteorological Agency and other official broadcasters as these systems move across the region.