Meteorologists have warned that the ash cloud could reach Scotland by Tuesday and spread to England, France by Thursday.
However the wind pattern remains changeable and the cloud could still be swept away from the UK.
The warning comes a year after another volcano wreaked havoc across the UK and mainland Europe.
Airlines have been warned the new ash cloud will drift, which could result in disruption to transatlantic flight paths. But experts said they saw little chance of a repeat of last year’s six-day closure of airspace.
So far Iceland, particularly the towns and villages to the south and east of the Grimsvotn volcano, have suffered most. Day turned into night when a thick cloud of ash descended on the area, smothering cars and buildings.
Grimsvoetn, Iceland’s most active volcano at the heart of its biggest glacier, began erupting late on Saturday, sending a plume of smoke and ash 12miles high.
So much ash was blasted into the sky that it blocked out the sun and covered nearby villages and farms.
“The higher level winds are blowing towards the northwest,” said Peitur Arason, a forecaster at the Icelandic Meteorological Office, adding that “low-level winds are ... blowing strongly towards the UK.”
While lower-level winds are close to the ground and thus will probably not manage to carry the ash as far afield, Arason said they would still “affect air travel.”
Bob Atkinson, travel expert at travelsupermarket.com says: “As news of the Icelandic volcano eruption hits, with it brings the same travel uncertainty as we experienced in April 2010. At this stage, it is business as usual except for flights to and from Iceland. For those who have booked a trip to Iceland, check with your tour operator or airline for the latest travel information.
He added: “Should airspace actually close, travellers are urged not to do anything without speaking to their airline or tour operator first, checking their website for further information.”