Adelaide will reach 27 degrees only three days after snow fell in the hills. On Wednesday and Thursday Adelaide had its coldest pair of October days in nine years, with the temperature failing to exceed 15.3 degrees. The Antarctic blast even provided snow to the Adelaide hills, an event that is rare in winter. Today will come as welcome relief as mostly sunny skies will prevail and the temperature will reach 21 degrees. Heat will arrive tomorrow and on Monday as temperatures will rise to the mid to high twenties with mostly clear skies. The sudden arrival of heat will be due to a northeasterly flow ahead of a trough that will draw heat from central Australia into South Australia. This heat will then move east and inland before another dose of central Australia's heat is directed into Adelaide on Friday and potentially the weekend. This heating will be stronger than this week, with temperatures likely to reach the 30's on at least one day.