Intense heat building up over the Pilbara is set to filter over coastal cities early next week. An extremely hot air mass baking over the Pilbara region is has allowed Marble bar to warm up to 44 degrees before 9:30 this morning. Along with Roebourne, the mercury has the potential to rise to 49 degrees this afternoon. Early next week, a low pressure trough is set to draw this hot air down the west coast presenting the risk of temperatures in the high thirties for coastal towns from Geraldton to Bunbury. At this stage, the axis of this trough is looking to be positioned in such a way that winds will tend offshore for most of the morning and early stages of the afternoon for Geraldton and Perth. Geraldton is set to see the temperature peak on Monday with the mercury potentially rising to 38 degrees. As the week continues, this trough will progressively draw hot air further south over Perth and Bunbury. Tuesday and Wednesday are looking to be the warmest days for the state's capital with the potential to see 37 and 38 degrees respectively. Meanwhile, 35 degrees is not out of the question for Bunbury on each of these days. Fortunately for residents of Bunbury, due to the fact that the southern flank of this trough is positioned nearby, moderating sea breezes are expected earlier in the afternoon than their northern neighbours. Temperatures will gradually cool towards the end of the week despite remaining well above average throughout the coming fortnight.