VAIL, Colo. (AP) _ America's largest ski resort opened today, delayed three days but not because of last month's $12 million arson attack.

The weather had just been too warm to make snow, resort executives said. Several other Colorado resorts also delayed their openings.

Until the weekend, daytime temperatures in the mountains were rising into the 50s, too warm to preserve any snow made by machines during the night when temperatures dropped to freezing.

Only 8 inches of natural snow had fallen but more is on the way this week as a weather front moves in from the Pacific Northwest.

The arson attack destroyed three buildings and damaged four chairlifts. No arrests have been made.

The Earth Liberation Front, a shadowy environmental group, claimed responsibility for the fires and threatened more action if Vail moves forward with plans to expand into roadless areas.