Southern Vietnam is blessed with a more equitable - and predictable - climate. Here the dry season lasts from December to late April/May, and the rains from May through November. Most of the rain falls in brief afternoon downpours, so you can still get out and about, though flooding can be a problem in the delta. Daytime temperatures rarely fall below 20°C, occasionally reaching 40°C in the hottest months (March to May). Once the rains start, humidity climbs to an enervating 80%.