Victor Harbor has a Mediterranean climate — dry summers, mild winters, and a reliable pattern of warm weather from November to April. The whale season (June to October) is the main reason to time a visit specifically: southern right whales enter Encounter Bay to calve and can be seen from the shore, the causeway, Granite Island, and The Bluff. September and October are often the best months for whale watching, with the highest concentration of animals in the bay.
Summer (December to February) is peak domestic tourism season — school holiday crowds, higher prices, and busy foreshore. The beaches at Port Elliot and Middleton get busy. Spring (September to November) and autumn (March to May) are the quietest and most pleasant times, with comfortable temperatures and fewer visitors. Winters are cool but mild by Australian standards — rarely cold enough to be unpleasant for outdoor activities.