Bangkok's immediate prospects remain uncertain, however, as the front lines in battling the flood from north, east and west of the city draw closer daily.
The relatively rosy longer term projection from the Flood Relief Operations Center came just a day after reports that Bangkok's main Chao Phraya river was overflowing its banks and at its highest levels in seven years.
People should not be too concerned because the spillover could be drained, said the center's chief, Justice Minister Pracha Promnok, in a televised news conference. He also said water in an overflowing main canal in Bangkok was receding, and drainage efforts east and west of the city were working well.
The situation was dire in many respects in the capital's northern outskirts and Thailand's central provinces, which suffered the worst of the flooding after heavy monsoon rains since July.
Off a highway heading north of the city, Associated Press reporters found people scrambling for safety in flooded streets.
The Thai military used boats to help rescue stranded residents near a domestic airport in northern outer Bangkok that has been the flood-operations headquarters and a shelter for evacuees.
Mothers walked in hip-high water with children strapped to their backs, while other people waded through the murky water holding belongings in plastic bags atop their heads.
There are concerns the Don Muang airport itself may be vulnerable, and the European Union canceled an aid-handover ceremony scheduled there Monday due to "unforeseen circumstances."
In Nonthaburi province, just north of Bangkok, a 7-foot (2-meter) crocodile was captured while resting on dry land outside a restaurant, presumably after pulling itself out of the surrounding floodwaters. Thai television showed the beast, which had reportedly escaped from a farm, with its snout taped shut and its scaly body covering most of a boat that was carrying it away.
An Associated Press photographer saw two crocodiles that had been killed in Nonthaburi, and unconfirmed recent reports have claimed up to 100 crocodiles may have escaped from farms in the region.
Prime Minister Yingluck Shinawatra has said the waters may take up to six weeks to recede to manageable proportions around Bangkok. The government has cautioned that rumors have been quick to circulate and people should check all information, advice that follows strong criticism of the government for missteps and confusion since the crisis began.
Residents of Bangkok and its suburbs have settled into a routine of waiting and worrying.
Many are hoarding supplies, and supermarket shelves have emptied faster than they can be restocked. Bottled water, batteries and canned food were among the first items to go.
At a supermarket in central Bangkok's business district — which is not under immediate threat — sandbags lined both entrances Sunday, forcing shoppers to step over to go inside. Many of the shelves were bare, with the handful of shoppers inside grabbing the few snacks that were left. Cat food and toilet paper were gone.
While larger stores in Bangkok have kept their prices fixed, smaller merchants were raising theirs in the flooded zones north of the city. A Rangsit resident, Taweetit Hongsang, complained that the price of a papaya, 10 baht (33 cents) a week ago, had shot up to 30 baht ($1).
The desperate battle to route the water away from the city has led to several conflicts in which people have used force to try to protect their own neighborhoods by removing flood barriers.
Bangkok Governor Sukhumbhand Paribatra said Sunday one crew of city workers was unable to carry out reinforcement of one barrier because of "a group of people opposing the mission and harassing" them. He said it was necessary to withdraw them "since they are not trained to deal with unruly and armed outsiders."
In evident response, Prime Minister Yingluck Shinawatra said she had delegated high-ranking police officers to protect workers carrying out anti-flood duties.
The flooding that began in August has killed 356 people in Thailand and the $6 billion cost estimate could double if Bangkok is badly hit.
The flooding is the worst to hit Thailand since 1942 and is proving a major test for Yingluck's nascent government, which took power in July after heated elections and has come under fire for not acting quickly or decisively enough to prevent major towns north of the capital from being ravaged by floodwaters.