This morning left many people wishing they could stay in bed as Jack Frost knocked on the door. In the Northern Tablelands, Glen Innes Airport dropped to nearly minus eight degrees, which is its coldest May morning since 2006. At Inverell, the mercury briefly dipped below freezing for the second morning in a row. While it is not unusual to see temperatures drop overnight as we head into winter, it is certainly a shock to the system compared to the recent warm nights. Murwillumbah residents will have certainly noticed the drop in temperature, with an 11 degree difference between yesterday morning and this morning. Mudgee in the Central Tablelands dropped to minus one in the early hours - the last time it was this cold was in September last year. In the ACT, the temperature finally dropped below freezing for the first time this year. By this time last year, Canberra already had seen sub zero temperatures eight times. Even Sydney-siders were struggling this morning as the mercury finally dipped below the long-term May average of 11.6 degrees, which was the first time this month. Parts of western Sydney saw their coldest morning so far this year. Richmond recorded 0.5 degrees, its coldest morning since August. Homebush also saw their coldest morning since August with 4.9 degrees. Clear skies combining with a cool airmass helped the temperature to plummet before sunrise. With winds remaining light, the cold dense air settled in. Cloud will slowly build over the state today ahead of a low pressure trough. With the addition of this cloud, a warmer morning is likely on Thursday. For some, the sound of raindrops on the roof may also warrant a sleep in. After another strong cold front on Saturday, frost is likely to return as early as Sunday.