In the Central Valley, where the main centres of population are located, the average temperature is 22°C (72°F) and the region enjoys a spring-like climate year round. In the coastal areas, the temperature is much hotter and humid, while the Pacific Northwest can be extremely hot and dry. The rainy season starts in May and finishes in November, although there are distinct regional variations. The ‘warm' dry season is December to May, though temperature differences between summer and winter are slight.

Lightweight cottons and linens most of the year, warmer clothes for cooler evenings. Waterproofing is necessary during the rainy season. Loose-fitting clothing is best. Wear neutral browns and greens for birding and wildlife viewing.