South-East Asia's second-largest economy, which is heavily reliant on tourism, likely contracted 3.3% in the first quarter from a year earlier, according to the median estimate of 11 economists in the poll. It slumped 4.2% in the final quarter of 2020.
On a quarterly basis, gross domestic product (GDP) likely shrank a seasonally adjusted 0.8% in the March quarter after posting growth of 1.3% in the fourth quarter of last year.
The latest coronavirus outbreak, which started in April and has accounted for more than two thirds of Thailand's total infections, has slowed domestic activity at a time the tourism-reliant country was preparing to reopen more broadly to foreign visitors.
Economists in the poll predicted full-year growth of 2.1% in 2021, after a 6.1% contraction in 2020. Analysts have slashed their forecasts in recent months from around 3% at the start of the year due to the outbreaks and a slow vaccine rollout.
The economy could shrink again in the second quarter from the previous quarter as most indicators remain weak, said Takit Chartchredsak, economist of Asia Plus Securities.
Increased exports, a key growth driver, and recent stimulus measures have lent some support, however.
Thailand's cabinet approved an additional economic relief package worth 255 billion baht ($8.13 billion)earlier this month to help people affected by the latest outbreak.
"A fresh fiscal thrust and export pick-up will help offset part of the impact, but the pace of turnaround this year will be slower than previously assumed," said DBS economist Radhika Rao.
In February, the National Economic and Social Development Council, which compiles GDP data, forecast 2021 GDP growth of 2.5%-3.5%.
It will give new projections on Monday (May 17). - Reuters