Parts of South Australia were soaked by the heaviest rain of the year and now bitter southerly winds are surging into the state. The cold spell is being driven by a developing low pressure system centred over western Victoria. This system is directing fresh to strong and gusty south-westerly winds through the state. The airmass has cooled significantly with the passing of a powerful front. Adelaide will only reach 13 degrees today, which is six below the average and potentially the coldest since July of last year. The wind chill factor will make it feel even colder. Moomba got to a balmy 29 degrees on Wednesday and is expected to be one of the warmest locations in the state today, with a top of just 19 degrees. The powerful front was also responsible for bringing widespread rain across the southern half of the state. The heaviest rain was focused over Adelaide and the Mt Lofty Ranges overnight, with falls of 10 to 30 millimetres. The city picked up 20mm to 9am on Thursday, the heaviest daily total in two and a half months. Verdun in the Mt Lofty Ranges picked up its heaviest rain since August with 33mm and Parawa gained 61mm in 24 hours, its heaviest in more than a year. The rain will ease to isolated showers this afternoon and evening as the low pressure system moves further south and east. The outlook is for another cold day on Friday, with isolated showers, cloud and brisk southwest winds. There will then be gradual warming through the weekend as skies begin to clear and winds ease.