Valledupar is hot year-round — temperatures in the city stay between 26 and 36 degrees Celsius throughout the year, with the valley trapped between two mountain ranges offering little relief. The rainy seasons run roughly April–June and September–November, bringing afternoon downpours that cool things slightly before the humidity returns.
The best time to visit, if you can manage it, is April, when the Festival de la Leyenda Vallenata takes over the city for five days of accordion competition, concerts, and celebration. This is the main reason most foreigners come to Valledupar, and it is worth planning around. Book accommodation well in advance.
The dry months of December–March and July–August are the most comfortable for general visiting, with clear skies and the river swimming spots in good condition.