The Barossa Valley is enjoyable year-round, but summer (December to February) can be very hot — temperatures above 40°C are not unusual, and many visitors find the heat oppressive for spending time outdoors or tasting. Spring (September to November) and autumn (March to May) are the most pleasant times. Vintage, in March and April, is the busiest and most atmospheric time of year, when the wineries are processing fruit and the valley smells of fermenting grapes. The Barossa Vintage Festival, held in odd-numbered years in April, is the longest-running wine festival in Australia.