Japan Meteorological Agency to extend weather forecasts to two weeks

The Japan Meteorological Agency (JMA) plans to extend its detailed weather forecasts from the current five to seven days to a two-week period. This initiative, aimed for implementation by 2030, represents the agency’s first major operational update in three decades.

The move is driven by the increasing frequency and intensity of extreme weather events, such as record heatwaves, heavy snow, and torrential rains, which are being exacerbated by climate change. An expert panel noted that longer-term forecasting serves as essential ‘soft infrastructure’ for climate change adaptation, helping citizens and businesses prepare for disasters and heatstroke.

Proposed updates also include extending the window for warning-level heavy rain and snow information. Additionally, the JMA intends to revise its monthly temperature comparisons; instead of using a 30-year average, which often results in forecasts simply stating temperatures will be ‘higher than normal,’ the agency will provide comparisons against more recent periods, such as the last three years, to better reflect current climate realities.