Aethopia
Hong Kong weather, wind and storms, on iPhone, Android and the web.
Today: live Observatory readings, rain bands, sun and Moon 
Map: global particle wind, a ten-day timeline, press any point to read it 
Storms: distance, heading, closest approach and the No. 8 chance
Six things it does
Today at a glance
Observatory conditions, the nine-day forecast, hourly detail, UV, air quality, sun and Moon.
Storm alerts
A notification when the tropical cyclone signal changes, a storm comes within 500 km, or a new storm is named; No. 8 and above at once, the rest held overnight.
No. 8 signal chance
Our own estimate in three-hour steps, clearly marked as not an Observatory forecast.
Particle wind field
A ten-day wind field on a sphere; press and hold to read temperature, pressure and gusts.
Aviation
VHHH runway components, METAR and TAF decoded, both ends of a flight and its distance from any storm.
Past storms
Mangkhut, Hato and others replayed against the station readings of the day.
Widgets
Questions
When does a notification arrive?
Three cases: the tropical cyclone signal is raised, lowered or cancelled (No. 1, 3, 8, 9 or 10); the nearest storm comes within 500 km of Hong Kong; a new storm in the western North Pacific or South China Sea is named by an agency. Anything involving No. 8 or above goes out at once; the rest is held between 23:00 and 07:00 and sent at seven. There is no daily digest.
How is my location used?
Only after you tap Allow location or turn it on in Settings; it is read once each time the app opens or returns to the foreground and is never tracked continuously. Within 50 km of Hong Kong the location is not kept and the app shows Hong Kong; beyond 50 km the coordinates travel with each request to draw the Here page, and the server neither logs nor stores them. See the privacy policy.
Where does the data come from?
Public data from the Hong Kong Observatory, the Japan Meteorological Agency, the US National Hurricane Center, the NOAA Aviation Weather Center, Open-Meteo and the Environmental Protection Department, among others; the No. 8 chance and the particle wind field are our own computation. See Sources and limits for each source and its licence.