Asking the sky what the hell it's playing at…
Every hour gets a drying score from how thirsty the air is (temperature and humidity, as vapour pressure deficit), how windy it is and how much sun is belting down. Rain re-wets the load. We add the scores up from the moment you peg it out until it hits 100%. It's a bloody good guess, not a promise. Forecasts come from Open-Meteo. In the UK and Ireland it uses the Met Office forecast.