Thai business operators expect the country's GDP to grow 4-4.3% in 2019 while exports have been tipped to expand 5-7% next year.
Kalin Sarasin, chairman of the Thai Chamber of Commerce, said they anticipate weaker local purchasing power in 2019 because of falling crop prices.
External factors undermining Thailand's economic growth include the fallout from Brexit and the ongoing trade war between the US and China.
"Thailand is suffering from both [aforementioned] external factors because Britain, the US and China are among the world's largest economies, so they affect global trade," Mr Kalin said after a monthly meeting of the Joint Standing Committee on Commerce, Industry and Banking (JSCCIB).
Mr Kalin said the JSCCIB projects inflation to hover around 0.8-1.2% next year.
Thai GDP is showing growth of 4.4% this year, with exports expanding 8% and inflation climbing 1.1%, the panel said.
"Local GDP in the fourth quarter is benefiting from the government's stimulus measures to boost local consumption, so the JSCCIB is confident GDP for the year as a whole will grow as expected," Mr Kalin said.
"Exports and tourism remain the key economic engines for Thailand, and the fourth quarter usually enjoys seasonal advantages with both sectors beefed up; moreover, Chinese tourists are expected to return to Thailand this quarter," he said, alluding to a recent drop-off in their numbers after a tourist boat sank in Phuket in July, killing dozens of Chinese.
The JSCCIB also forecast that the government's tax breaks for shoppers from Dec 15 to Jan 15 would stimulate domestic consumption by 10 billion to 15 billion baht.
Mr Kalin said these measures would contribute 0.1-0.2% of GDP.
Additionally, a New Year's package for 11.1 million holders of welfare smartcards, issued to help relieve poverty, is expected to shore up the economy from late this year until the middle of next.
In Thailand, those who earn less than 100,000 baht a year are considered to be living below the poverty line.
Supant Mongkolsuthree, chairman of the Federation of Thai Industries, said scheduling the election in February is aimed at increasing companies' and investors' confidence, in line with the government's roadmap.
Despite this positive factor, however, Thai GDP is unlikely to be galvanised throughout 2019, he said.
Mr Supant said the government's investment projects, mainly for the flagship Eastern Economic Corridor (EEC) scheme, would be the main contributor to the country's investment and construction sector as it seeks to expand next year.
"The private sector will have more confidence to invest and expand its operations in Thailand," he said.