Colonia del Sacramento weather in September

September is the join between winter and spring here and regulars describe it as pleasant with a gap in it: warm enough by day, cool and fresh once the sun goes, so an evening layer is not optional. Our row gives 19.3C days feeling like 17C over 11.6C nights that feel like 8C, with a 24.1 kph wind doing most of that. The spring flowers are starting. The jacarandas are not - they begin in the first week of November and peak around the 15th to the 20th, so anyone booking this month for the purple streets has come six weeks early. Rain is moderate at 65.6mm across 6.1 days. The record: humidity 74 percent, 8.9 hours of sun and AQI 34.

Colonia's own forum doesn't have much May-specific weather chatter, but one useful data point came up in a beach thread: swimming season here doesn't really start until around Christmas, which confirms May sits well into the cooler off-season. The destination's own climate record fills in the rest - mild autumn days in the high teens C, cool nights, and only occasional rain. It's actually a pleasant month for what Colonia is really known for: wandering the cobblestone, Portuguese-influenced old town without summer crowds or heat.

Forum posters are candid that November weather in Uruguay isn't a guaranteed warm, sunny stretch - it's generally decent for touring but shouldn't be assumed reliably nice. For the town itself, posters consistently praise the UNESCO-listed historic quarter (founded 1680) for its Portuguese-influenced architecture and winding streets, often compared to old Lisbon, calling it clean, safe, and notably friendly and slow-paced. The fast ferry from Buenos Aires (as short as 15 minutes on some routes) makes it an easy day trip or overnight, and posters recommend an early start and staying at one of the town's posadas to properly soak in the pace rather than rushing through on a single-day visit.