The recent blast of cold air is having a wide-reaching effect, with unseasonable cold from Tasmania to the northern tropics. It's been at least 30 years since a series of cold fronts has had such an impact this early in the year, affecting almost every state and territory. One front, which moved through southeastern Australia on Monday was followed very swiftly by a much stronger cold front less than two days later. Together they dried and chilled the atmosphere so much that the drier, colder air penetrated well into the tropics with far-reaching southerly winds. On Wednesday, Melbourne had its coldest day this early in the year since 1970, struggling to 12.2 degrees. It took until winds eased on Wednesday night and Thursday for the rest of the eastern Australia to feel the effects of the extraordinary cold. It's been more than 50 years since Canberra, Sydney and even Mt Isa have been as cold this early in the year. At about sunrise on Thursday Canberra was minus 5.3 degrees, Sydney 7.9 and Mt Isa 4.7. It's been at least 40 years since Tennant Creek got as cold as 9.4 this early in the year. Whilst days will gradually warm up into next week, nights will remain chilly.