Esperance has a Mediterranean-style climate: warm, dry summers and mild, wet winters. The best time to visit depends on what you're after.
Spring (September–November) is the top season for wildflowers. The heathland in Cape Le Grand National Park and along the Great Ocean Drive produces extraordinary displays of banksias, hakeas, wattles, and native orchids. This is also the whale-watching season — southern right whales and humpbacks move through the Recherche Archipelago on their migration.
Summer (December–February) is warm and dry, with long days and calm seas ideal for swimming. Beach conditions are at their best, and the days are long enough to see both the national parks and the town beaches in a single day. It gets hot — mid-to-high 30s — but sea breezes usually arrive in the afternoon. The Christmas school holiday period is the busiest; Lucky Bay campground books out months in advance.
Autumn (March–May) is a good compromise: the summer crowds have gone, the sea is still warm from summer, and the weather is stable. Winter (June–August) is quiet, mild, and wet enough to turn the landscape green. Storms can close some coastal roads, but the wildflower season starts building in August and the whale-watching season begins.