Melbourne is set for blazing heat today, but the hot spell will be short-lived. Gusty northerly winds will drag heat right across the city, with temperatures likely to exceed 40 degrees in many suburbs. Melbourne won't be alone in the suffering under this intense heat, with northwestern parts of the state likely to reach 45 degrees. This fierce heat is combining with hot and gusty winds, which had prompted the CFS to issue a Total Fire Ban for much of the state. Fire danger is forecast to reach 'Extreme' in the Mallee, Wimmera and South West and well into the 'Severe' rating in central parts of the state . So far, Melbourne has seen only one day which has exceeded 40 degrees this summer (19th December), and the previous summer (2014/2015) there wasn't a single day that exceeded 40 degrees. However, the summer of 2013/2014 was a very different story, with seven days reaching 40 degrees or more, four of those days occurred consecutively in January 2014. A windy and stormy change will reach western parts of the state this afternoon. For Melbourne, it will stay hot into the evening before the squally change arrives much later in the evening. This change will drop temperatures by as much as 20 degrees by early morning. On Thursday, conditions will be remarkably different. The blistering heat will be replaced by a much colder airmass. Temperatures are likely to be 20-to-25 degrees colder across most of the state. Winds will remain cool and gusty throughout Thursday, making it feel even colder than the forecast of 19 degrees in the capital. A raincoat may come in handy, with a few showers also on the cards. Friday will be similar, although wind will gradually ease and showers clear during the day. Over the weekend, the sun will make an appearance, helping to warm Melbourne to the low-30's by Sunday.