Dry, gusty northerly winds are becoming hot in South Australia, blowing dust, damaging crops and increasing fire danger. The dry northerlies have been gusting 50-to-70km/h in central and western parts of the state, strong enough to damage crops and generate extreme fire danger ratings. Up until 10am the strongest wind gust was recorded at Cleve, 80km/h, strong enough to damage barley crops. The highest fire danger ratings in the state have also been in the west, where they have already reached the extreme category, one category below catastrophic. Ceduna experienced extreme fire danger overnight. At 2am the temperature was 30 degrees, humidity only five percent and northerly winds were gusting 50km/h. It slowly cooled to 26 degrees by sunrise before a westerly wind change arrived just before 9am. The low pressure trough which brought this cooler change is due to arrive in Adelaide late this afternoon or early evening, cooling the city to the low 20s later in the evening. As the trough travels east across the North West Pastoral and Eyre and Yorke Peninsula, northerly winds ahead of it will become hotter and stronger. These northerlies will whip up more dust, threaten crops and make any grass-or-scrub fires difficult to control. A fire weather warning and barley growers weather advice have been issued.