Overview
- Spain's national meteorological agency AEMET issued warnings on Sept. 16–17 for a marked drop in daytime temperatures across much of the peninsula driven by a cold upper‑level air mass and a surface front.
- AEMET also flagged a high risk of strong to very strong afternoon and evening storms with hail and very strong wind gusts in Catalonia, Valencia, Teruel, east Castilla‑La Mancha and Mallorca.
- Local forecasts show strong regional contrasts inside Spain, with many Cantabrian and interior areas turning much cooler while Galician coastal towns report clear skies, mid‑20s Celsius highs and virtually no rain.
- In Argentina the Servicio Meteorológico Nacional reported a progressive warming through Friday with no active national alerts and then modelled an unstable system that should bring rain and thunderstorms from Friday night into the weekend, focused on NOA, NEA and mountain zones.
- The pattern reflects a routine mid‑September transition: an upper‑level cold pool and front produce rapid cooling and convective hazards in the Northern Hemisphere case, and a northward flow ahead of an unstable system yields transient springlike warmth before weekend precipitation in the Southern Hemisphere, with implications for local agriculture and water balance.