The natural air conditioner — how a sea breeze keeps hot air away from the coast

More than 85 per cent of Australians live within 50 kilometres of the ocean, but the variation in weather across any slice of this narrow coastal band is substantial. The cool relief along the coast will result from a sea breeze, but what causes this natural air conditioner? Onshore winds alone do not indicate a sea breeze has formed, even though a flow off the ocean can still generate a substantial temperature contrast if winds are near parallel to the coast. Surprisingly though, it's Perth, lying further north than Adelaide and Melbourne, which has the most frequent and strong sea breeze of Australia's capitals, occurring on nearly 60 per cent of days. When a high-pressure system is absent, winds are often too strong for a sea breeze circulation to form, most notable when very hot and dry air blows in from the nation's interior.