There are around 42,000 streetlights across the county that are switched off between the hours of midnight and 6am.
Coun Richard Davies, Executive Member for Highways, said: “Over the next few weeks, you might notice that the part-night streetlights start to go off and come on at different times.
“Please be assured that this is not due to a technical fault. The street lights have sensors that monitor the number of daylight hours, which is how they set their internal clock.
“During the autumn, the lights enter a period of adjustment, when their timings may vary as they adapt to the switch to Greenwich Mean Time.
“Unfortunately, this is unavoidable, but it is only temporary.”