The 64m-high turbine 'snapped' and fell over at a wind farm in the remote townland of Maas, between the Co Donegal villages of Glenties and Ardara.
It came during a weekend of freak late-March weather, which saw thousands of homes in the North plunged into darkness as high winds and snow hit east Ulster and north Leinster.
Forecasters have warned that while the worst of the snow and wet weather has passed, the bitterly cold easterly wind will continue right through until Easter with temperatures falling to as low as-8C.
The collapse of the turbine, one of nine Danish-built Vestas devices on the Donegal wind farm, was being investigated yesterday by both the owners of the site, a group of Dublin investors and Donegal County Council. Vestas is expected to send engineers to inspect the wreckage later this week.
The collapse of the turbine has worried residents of nearby Strathboy, where 100m-high turbines are planned.
Local county councillor Terence Slowey told the Irish Independent: "There is a great deal of concern that this could happen."
The Glenties Windfarm Information Group, which has opposed plans for more turbines in the area, called for "a full investigation".
"What would have happened if the one nearest the road had collapsed?" asked one cyclist on the route yesterday.
"It would certainly worry you that this could happen."
In a separate incident at the weekend, a 40ft lorry was blown off the N56 near Loughanure, also in west Donegal.
And the easterly airflow is going to bring more cold weather with the possibility of snow, said Mark Dunphy, editor of Irish weather website meteotimes.net. He also said March's temperatures could turn out to be the lowest of any month in more than two years.
"So far this month, temperatures are running between 2C and 3C below normal (1981-2010) across the country and with these cool conditions likely to continue for the remainder of the month, March 2013 will very likely finish colder than any of the preceding winter months, and the coldest month - relative to average - since December 2010," he said.
He warned of the possibility of further snow today in Leinster.
"The days mid-week will be very cold with about equal mixtures of cloud and sunshine although tending to be more sunny in the west, with greater risk of snowfall in isolated streamers near the east coast, south coast and parts of Ulster," he said.
"Over time, Meath, Dublin, Wicklow, Waterford and inland south-east and east Ulster are regions most likely to see at least slight accumulations during the period."
He added that the cold weather would continue over the Easter weekend with the possibility of a "significant snow event" in eastern parts on Good Friday.