Heat reached its peak in Western Australia's Kimberley and Pilbara on Friday, exceeding 46 degrees in parts, the hottest it has been in decades for some. Fitzroy Crossing was the first to exceed 46, doing so just after lunch, on its way to 46.4 degrees. This turned out to be its hottest day in more than 20 years, beating its previous high of 45.7, also in December, in both 2009 and 2004. The record for that area is 47.9, at a nearby composite site, set in January 1969. Mid-afternoon yesterday, Marble Bar overtook Fitzroy Crossing, to become the state's hot spot. The 46.5 degrees recorded at Marble Bar is a three-year high for the town. This is also the highest temperature recorded in WA this early in the season since Roebourne reached 46.8 degrees mid-November three years ago. A heat trough which develops each year at the end of the dry season has been hovering over northwestern Australia for a few weeks, allowing the region to consistently reach the forties, a few degrees above average. The heat trough has been left virtually uninterrupted for the past few weeks, The delay in the northern Australia monsoon has meant storm activity has been down on normal, hence daily sunshine has been up on normal also. On Saturday, the Marble Bar and Fitzroy Crossing areas should reach about 46 degrees again. Marble Bar should do it again on Sunday and the mid forties in the following days. Gradual cooling should then take place as the trough gains cloud and and brings increased shower and storm activity.