Olympia has the same temperate marine climate as the rest of the western Puget Sound — mild, wet, and reliably grey from October to May, with a brief but spectacular dry summer.
Summer (mid-June through September) is by far the best time to visit. Daytime highs run in the low-to-mid 20s°C, rainfall is minimal, and the long evening light shows the Olympic and Cascade mountains at their best. The Farmers Market is at full strength.
Winter (November–March) is dark and damp, with relentless drizzle rather than dramatic storms. The annual Olympia Film Festival in November and the various holiday events around the Capitol campus give some structure to the months.
Spring (April–May) brings the city's signature event — the Procession of the Species — a giant Earth Day parade of homemade animal costumes through downtown, usually held on a Saturday in late April. The cherry blossoms on the Capitol campus peak shortly afterwards.