The main N22 Killarney to Farranfore and Tralee Road was closed in both directions due to a jack knifed truck blocking the road.
Gardaí and council crews are at the scene and it has now been cleared.
KCC says gritters are clearing the road to get traffic moving but patience is required and the road should be avoided until traffic is moving freely again.
The road between Farranfore and Killarney is now back to two lanes.
There are extensive tailbacks in both directions and leading to a backlog on the Killarney by pass.
Difficult conditions are also being reported at Spa, Tiernaboul and at the county bounds.
KCC say journeys on the N22 between Cork and Kerry should be deferred until snow ploughs can deal with recent heavy snow which has already caused multiple vehicles to be abandoned.
The L2015 from Tralee to Kielduff/Lyrecompane and Knocknagoshel is impassable due to cars coming off the road and getting stuck.
Google maps are sending motorists on to the N21 from Castleisland to Abbeyfeale according to KCC but they say that this is also impassable.
The road from the Golden Nugget in Killarney to Faha is blocked and cars are also getting stuck in Abbeydorney and Listellig.
The Oakpark Road in Tralee is blocked in both directions.
There are also difficulties at Leith Cross,and in Killorglin.
The Conor Pass remains closed and KCC and Gardaí are advising that all highs roads be avoided completely including the N71 Caha Pass, Healy Pass, Molls Gap, Ballaghasheen, Ballaghbeama, Lyrecompane, Mountain Stage and Quills Cross on the N70.
The N23 is being ploughed but passable according to KCC, they say the N70 is still tricky with cars abandoned at Mountain Stage.
There are significant changes to all Bus Éireann Services in Kerry today and possibly tomorrow and passengers should check before travelling.
The Council’s severe weather helpline is available at 066 718 3588.
The ambulance service is also appealing to people not to travel.
Killarney House and Muckross House and main entrances will remain closed.
NPWS management will reassess conditions on Tuesday.
Kerry County Council have thanked Civil Defence personnel and Kerry Mountain Rescue who are helping to rescue people from vehicles that have become stuck before nightfall sets in.
They are also advising that abandoned vehicles, fallen branches and other unseen debris makes driving in the snow after dark even more hazardous.
They say to only drive overnight is your trip is absolutely essential and to be prepared to be stuck in your vehicle .