With temperatures set to dip below zero in some parts of the region, gritting will begin along routes in Lancaster, Fylde and Wyre this afternoon, with gritting in East Lancashire set to take place this evening.
A forecaster from the Met Office warned residents to expect "a cold night with clear skies and widespread frost" as well as "a risk of fog patches developing through the early hours".
Motorists are advised to drive carefully even on treated surfaces.
Priority routes only cover a third of the highway network and ice patches can develop on treated surfaces caused by water run-off from fields or other sources. Ice is most likely on untreated surfaces.
Priority routes are determined as:
++ Non-trunk Motorways and 'A' roads which are the main routes across Lancashire;
++ 'B' roads which are routes in and out of towns; roads which lead to hospitals, emergency service stations, main employment centres, and important public transport routes;
++ Single routes into villages.