The baht closed at 32.90 to the US dollar on Thursday, sliding from 32.84 at the start of the day.
Krungthai Bank market strategist Poon Panichpibool said foreign investors had decided to sell their assets in Thailand due to uncertainty caused by the Covid-19 situation in the country, and this would lead to a gradual weakening of the baht.
This, in turn, will lead to importers exchanging the Thai currency for dollars, or other foreign currencies.
Poon added that the both the dollar and pound would strengthen due to market players' concerns about the Covid-19 situation around the world, which had increased the demand for safe haven assets.
In addition, this strengthening is another factor in weakening the baht, he added.
Meanwhile the pound sterling has climbed again to 45.25, rising from Wednesday's 44.90.
Some analysts predict the British Pound is set to climb all the way back up to 50 baht by the year end.