Reservoir Watch

In the three months to 21 September 2026, none of the 17 reservoir sites we track in Hong Kong was short of rain. The 17 reservoirs were 85.8% full on their latest readings.

“Much less rain than normal” means the last three months were drier than about five in six of the same seasons on record at that point; “extremely little” drier than about thirty-nine in forty. The measure is the Copernicus Global Drought Observatory's three-month Standardized Precipitation Index (SPI-3), on a 25 km grid; the first threshold is roughly where the U.S. Drought Monitor starts D1 (moderate drought), so this headline reads like the Monitor's, though the Monitor also weighs soil moisture, streamflow and local reports. All of it describes conditions on the ground, not how much water is stored; a reservoir can be full after a dry season and low after a wet one. Source: drought.emergency.copernicus.eu. European Drought Observatory / Global Drought Observatory, https://drought.emergency.copernicus.eu © European Commission – JRC. Licensed CC BY 4.0.