A rainy-season front will bring precipitation to Kyushu and Shikoku on Tuesday before moving northward toward Honshu [1].
The progression of this front marks the transition into the rainy season for much of the Japanese archipelago, increasing the risk of heavy rainfall and flooding in affected regions.
Rain is expected to reach Kyushu on Tuesday morning, with precipitation moving into Shikoku around noon [1]. The front is projected to shift north on Wednesday and Thursday, eventually stalling over Honshu later in the week [1].
While much of the country remains sunny for now, southern regions have already experienced the seasonal shift. Amami entered its rainy season around May 3, 2026, which was about nine days earlier than the average [2]. Okinawa also entered the rainy season in early May 2026 [3], though reports indicate the region is now nearing the end of its rainy season [1].
Forecasters are monitoring the potential for severe weather as the front progresses. In Kagoshima Prefecture, there are concerns that linear precipitation zones could develop, leading to heavy rain [4].
In the north, temperatures remain mild. The maximum temperature forecast for Sapporo is 25°C [1].
There are some contradictions regarding the overall timing of the season's onset. Some forecasts suggest the rainy season may begin later than average this year [3], while other reports indicate that Hokuriku and Tohoku could enter the rainy season as early as this week [1].
“A rainy-season front will bring precipitation to Kyushu and Shikoku on Tuesday before moving northward toward Honshu.”
The stalling of the rainy-season front over Honshu typically leads to prolonged periods of precipitation, which can saturate soil and increase the likelihood of landslides. The discrepancy in onset timing for northern regions suggests a volatile atmospheric pattern, requiring residents to monitor local alerts for linear precipitation zones that can cause flash flooding.
