Temperatures are set to soar in Melbourne on Saturday before a cool and thundery change arrives in the early evening. Melbourne will experience its second very hot day in just over a week, with mercury likely to reach 37 degrees. The sun will shine throughout the day and hot, gusty northwesterly winds will hold out any sea breezes. It will be important to keep drinking plenty of water during the day and avoid staying out in the sun for long periods. Relief will come around dinner-time as the strong northerly winds tend southwesterly, bringing a cool change. The change will be followed promptly by a few showers and the chance of a brief storm or two. On Sunday it will be a completely different story, with a couple of early morning showers and the temperature only reaching 20 degrees in the afternoon. This is 17 degrees cooler than the day before. Monday to Wednesday will see sunny skies return thanks to a high pressure system, with temperatures climbing back above 30 degrees by the middle of the week.