The country registered 18,953 more Covid-19 cases and 30 new fatalities during the previous 24 hours, the Public Health Ministry announced on Sunday morning.
This compared with the 29 coronavirus-related fatalities and 18,885 new cases reported on Saturday morning.
There were 18,770 local cases in the general population and 183 imported cases.
The number of new local cases has now risen for six consecutive days dating back to last Tuesday, when the country logged 14,177 infections.
Bangkok led new infections with 2,690 cases, almost three times higher than the second-placed Samut Prakan, which logged 975 cases, according to details released by the Centre for Covid-19 Situation Administration on Sunday afternoon.
Chon Buri had the third-highest infections with 828 cases, ahead of Nakhon Si Thammarat (810), Nonthaburi (762) and Phuket (549).
Travellers from Russia led imported infections with 50 cases, 20 more than Myanmar, which came second. All Covid-positive new arrivals from the two countries were foreign nationals.
The 30 new fatalities were between the ages of 28 and 93, all of them Thai nationals.
Bangkok logged the most new deaths at nine, followed by five in Samut Sakhon and two in Lop Buri.
Pathum Thani, Samut Prakan, Kalasin, Khon Kaen, Chiang Rai, Sukhothai, Phattalung, Phuet, Kanchanaburi, Chanthaburi, Chachoengsao, Prachin Buri, Ayutthaya and Sa Kaeo had one death each.
On Saturday, 13,962 Covid-19 patients were discharged from hospitals after recovering from the coronavirus, while 162,460 people received Covid-19 treatment at hospitals, including 747 seriously ill patients and 189 dependent on ventilators.
Since the pandemic started in early 2020, there have been 2,712,315 Covid-19 cases, including 488,880 cases this year, with 2,527,231 complete recoveries to date.
The accumulated death toll stood at 22,624 since the beginning of the pandemic.
The highest number of Covid-related fatalities in a 24-hour period was 312 recorded on Aug 13. The highest number of cases was 23,418 on Aug 18.
Global Covid-19 cases rose by 1.59 million in 24 hours to 423 million. The worldwide death toll went up by 8,093 to 5.9 million. The United States had the most cases at 80 million, up 41,443, and the most deaths at 959,130, up 715.
Thailand ranked 32nd with its accumulated 2.7 million cases.