Frost and shallow mist within local valleys around my local area southeast of Melbourne, Australia from September 2018.
A series of cold fronts traversed the area directing a cold and dry airmass over Victoria which, when combined with a high-pressure ridge that moved over Victoria following the cold front passages, promoted clear skies and light winds. This enhanced the radiative cooling of the ground allowing it to cool quickly, promoting low minimum temperatures (0.5掳C was recorded on this morning) and frost.
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From @theloneisobar