Portland's climate is typical of coastal western Victoria — cool and changeable year-round, with prevailing westerlies off the Southern Ocean keeping temperatures moderate. Summers (December–February) are pleasant, rarely reaching the scorching heat of inland Victoria, with highs around 20–24°C. Be prepared for wind on most days.
Winter (June–August) is the best time to visit for whale watching. Southern right whales arrive in Portland Bay from June onwards to calve in the sheltered waters, and sightings from the shore or the breakwater are common. Bring warm layers — winter temperatures hover around 8–14°C and the wind can be biting.
Spring and autumn offer mild conditions and fewer visitors. The wildflowers at Cape Nelson State Park are at their best in spring (September–November).