The country's Flood Relief Operation Command (FROC) reported that flood defense measures in low-lying Bangkok have held and that the bloated Chao Praya River has not risen any further.
There had been fears that further heavy rain over the weekend combined with the spring high tides would overwhelm parts of the city.
"The water situation in Bangkok city is no longer a worry and today is the end of the high tide period," FROC spokesperson Wim Rungwattanachinda told CNN.
However, Irrigation department director general Chalit Damrongsak warned the situation remained critical as water from low-lying areas north of Bangkok still needed to drain.
"It is not over," he said, in quotes carried by Agence France-Presse.
So far, 307 people have been killed during months of monsoon rains across Thailand, with more than 8.6 million in 61 provinces affected by the rising floodwater.
Asia's wet and wild summer explained
More than 500,000 square kilometers -- an area the size of Spain -- have been affected by the floods in Thailand, Cambodia, Vietnam and Laos, according to CNN meteorologist Jenny Harrison.
In the ancient city of Ayutthara, one of the worst-hit areas, officials said the floodwater was starting to recede and flow towards the rivers.
The temples and monuments in the UNESCO-listed historical city have been submerged for days, prompting concern that much of the water damage will be permanent.
Meanwhile, a massive effort is underway to protect the Navanakorn Industrial Park to the north of Bangkok. The giant complex -- one of Thailand's largest -- houses a number of companies that produce electronics and components for the automotive industry.
According to the Bangkok Post, 600 workers, civilian volunteers and soldiers were working around the clock Sunday to strengthen defense walls on all sides of the facility as the water continued to rise.
Other manufacturing sites north of Bangkok, such as Rojana Industrial Park, were forced to halt operations as the floodwater hit. Honda last week said the closure of its plant there affected the production of at least 4,500 cars.
The Thai finance ministry says overall damage from the floods could be more than $2 billion, with the worst yet still possibly to come," according to CNN's Paula Hancocks.
Floods are an annual occurrence in the country but it has been particularly acute this year.
Thais across the country are donating food, water and clothing to help the worst-hit areas. Authorities said donations have far surpassed previous years.
The government said that it has received $2.07 million in donations, including help from other countries, by Sunday. The United States said it is sending 26 helicopters to help the relief effort, invaluable as more roads turn to rivers and become impassable.
United Nations agencies also are on standby, while the World Health Organization has offered emergency health kits.
