The charity's director general, Fiona Reynolds, yesterday called on the government to develop a strategy for dealing with the major problems from the threat.
Reynolds pointed to a series of examples where the trust had faced large repair bills following freak weather conditions closely associated with climate change.
One case was the Bocastle flood of 2004 ( pictured). The Trust, Reynolds said, had faced a repair bill of over £1.4 million. She added that this was a pointer to a future where torrential downpours of this type are expected to become more common.
Many other properties - including Grade I-listed Tyntesfield in Somerset - have suffered damage as their historic drain and guttering systems have proved unable to cope with torrential rain.
Exceptionally long periods of dry weather have also taken their toll. For example, the stream at Hughenden Manor in Buckinghamshire dried up entirely for the first time last summer. As a result, the beech trees, an intrinsic part of the estate's historic landscape, are coming under increasing strain.
'Climate change has implications for just about everything the National Trust does,' Reynolds said.
'We have to learn from our recent experiences of floods, storm damage and seasonal change, and recognise that the ways in which we look after our properties will increasingly be led by the impacts of a changing climate.
'Climate change is a here-and-now issue and we need to adapt to it fast,' she added.