No further ash drifts are expected to reach the continent in the coming 24 hours, he said.
As the cloud moved northward, German authorities halted takeoffs and landings at Munich airport at 1300 GMT but said high-altitude overflights remained possible.
Portuguese airports cancelled 223 flights, including 119 at Porto and 71 at Lisbon.
The Irish Aviation Authority ordered Ireland's five westernmost airports to close on Sunday afternoon.
However Ireland's three biggest airports in Dublin, Shannon and Cork were expected to stay open because the cloud is remaining off the country's Atlantic coast.
Trans-Atlantic connections were diverted around a larger patch of cloud stretching from southern Greenland to the coast of Portugal, adding several hours to flights between Europe and North America.
This also caused congestion as airlines tried to squeeze their planes through remaining routes.
Weather forecasts said that the ash would gradually dissipate as it spreads to southern parts of Germany, the Czech Republic and Austria by Sunday night.
With volcanic eruptions weakening, the plume in the mid-Atlantic was also slowly clearing.
It appeared that the volcanic ash was heading eastward and would be largely out of German airspace by midnight (2200 GMT) on Sunday.
Lawrence Lee, Al Jazeera's correspondent in Madrid, the Spanish capital, said that there were positive signs.
"The contingency plans that the airlines and airports have had time to put into place since the first eruption are starting to have a beneficial effect," he said.
"It looks like the airports and airlines are starting to take the fact of continued eruptions as a fact of life, move people not necessarily to exactly where they want to go but close enough and then get them overland to their final destinations."
Airspace across Europe was almost completely shut down for around a week last month after Eyjafjallajokull erupted and threw up an ash cloud over most of the continent.
But the authorities reopened airspace and airports after emergency talks between European governments, airlines and regulators.
The international airline industry body, Iata, said last month's shutdown had cost airlines about $1.7bn and called on governments to pick up at least part of the cost.
Eurocontrol said more than 100,000 flights to, from and within Europe had been cancelled between April 15 and 21, preventing an estimated 10 million passengers from travelling.