Demand is always higher in the northern hemisphere's summer,...

Demand is always higher in the northern hemisphere's summer, mainly due to people going on family vacations. It's alot different than Australia where we have beautiful weather year round, people go into hibernation and do most their travelling and driving in the warmer months. The fuel used in summer is also different from their winter fuel and burns quicker.

Also most factories will carry out their maintnance and shut downs in the cooler months and go full production in the warmer months.