Chiang Mai tourism operators are hoping the province's unsafe levels of PM2.5 air pollution lessen later this month as the Songkran holiday draws near.
The Thai Hotels Association said the polluted environment is affecting tourism this month as fewer bookings have been made.
The average occupancy in March is forecast to reach 50-60%, largely guests who booked before the air pollution, according to the association.
The Tourism Authority of Thailand said the government's hotel subsidy campaign, which was fully booked last week, recorded a low booking rate for Chiang Mai.
The province still lacks a long-term plan to battle the annual problem, the association said, adding "Advanced bookings don't look good for April despite the popularity of the Songkran holiday."
Water splashing around Chiang Mai's moat has long been a popular activity for visitors during the festival.