Vehicles are moving slowly southbound on the A1 between the A607 at Grantham and the A151 due to heavy traffic.
The Highways Agency says normal traffic conditions are expected by 6.30pm.
Meanwhile Lincolnshire Police is warning drivers of dangerous conditions overnight as temperatures drop to freezing. There has been no further snowfall in the Grantham area but snow on the ground is freezing and together with black ice is causing potentially hazardous conditions on many roads.
A police spokesman said: “Roads across Lincolnshire continue to be hazardous due to ice. Untreated roads worst affected, but caution should be exercised on all roads whilst the icy conditions persist.”
The Met office says temperatures in the area will drop to -3C tonight and even lower in rural areas.