Customers in the Hargraves, Maitland Bar and Avisford areas were without electricity following an outage that occurred at 7.47pm on Wednesday evening.

An Essential Energy spokesperson confirmed the cause of the outage.

"Crews worked as quickly as safety allowed and by approximately midnight were able to restore power for 169 customers but were then hampered in restoring power to the remaining 209 customers by foggy conditions combined with step terrain," they said.

"In daylight, a fallen powerline was found in the Bishops View area and once this was fixed power was restored to all customers at 12.23pm on Thursday.

"Restoration efforts were difficult due to the location, and in particular the terrain, where the powerline fell."

Bureau of Meteorology data shows it was chilly overnight in Mudgee with a low of 6.3 degrees, while the 'feels like' temperature was a few degrees lower at 3.2

Essential Energy's website provides information on planned and unplanned outages, with customers urged to contact 13 20 80 if they have an enquiry.