The victim, identified as Nan-resident Tirat (surname withheld), 63, was visiting the Priew Waterfall National Park with six of her friends.
Her relatives said she and her friends drove to Chanthaburi and stayed overnight at a hotel on the beach before heading to the park on Sunday morning.
At about 8.30am, when Tirat was returning to her car, a sudden gust of strong wind knocked down four power poles and some trees. One of the poles landed directly on her, killing her instantly, officials said.