Cuernavaca's reputation as "The City of Eternal Spring" is broadly earned — the climate is mild and comfortable year-round. At 1,500 metres, temperatures rarely exceed 30°C in the warmest months or drop below 10°C at night in winter. Rain falls mostly in the afternoon and evening during the wet season (June–October), but mornings are generally clear.
The dry season (November–April) is the most popular time to visit, with reliably clear skies. December and January can be lightly cool in the evenings; bring a layer. Easter week (Semana Santa) brings large crowds as Mexico City residents escape to Cuernavaca's warmth — book accommodation well in advance. The same applies to Day of the Dead (late October/early November).
The wet season is perfectly fine for visiting — the afternoon rains are usually brief and dramatic, and the city and surrounding countryside are greener. Xochicalco and Tepoztlán are particularly beautiful in September and October when the rains have finished and the vegetation is lush.