The rescue mission has faced a ideal storm of obstacles since it began, including monsoonal rains, a lack of oxygen in the cave and the fact that numerous boys trapped inside don't know how to swim let alone dive.
Thai officials are stressing that they may have to act very soon - meaning within the next couple of days.
Thailand's monsoon season runs from July to October and, while the past few days have been relatively dry, the long term forecast is rain for months.
The governor's midnight news conference, held just as a drizzle started to fall over the muddy, chaotic rescue site, underscored the lack of a good option to free the boys and their coach after they were found alive Monday night.
Gov. Osottanakorn said "air is a major issue", but added that United Kingdom experts had confirmed the conditions in the chamber where the children are located were "all right". The tunnels are pitch black.
The boys, he added, "cannot dive at this time" and are not ready to make the nearly six-hour journey out of the cave.
It came as authorities admitted that time is running out to get the boys out of the caves, where they have been stuck for two weeks since June 23. Such is the volume of water extracted that entire nearby fields have been transformed into lakes.
Authorities have been racing to pump out water from the cave before more storms raise the water level again.
Dark clouds drift ominously overhead.
"Once the heavy rains were going to hit, it was always going to be the deciding factor".
The chamber in which the boys are located is no longer thought safe.
But with their potential path out of the cave now submerged, there are fears they could be stuck there for weeks or even months.
Divers inch further into the cave, as an operating base is set up inside and hundreds of air tanks and other supplies are pulleyed in.More news: Dominica Under Hurricane Watch as Beryl Heads Towards Lesser Antilles
More news: North Korea says talks with Pompeo were 'regrettable'
More news: OnePlus 5 to get faster software updates
Late Friday, Thai officials were still trying to come up with a workable extraction plan for the group trapped for almost two weeks deep inside the cavern, stoking fears that all available options remain too risky. When I get out I will go to eat.
Each day rescuers at the camp talk of differing strategies.
More than 100 exploratory holes have been bored - some shallow, but the longest 400 metres deep - into the mountainside in an attempt to open a second evacuation route and avoid forcing the boys into a unsafe dive through submerged tunnels.
The parents have also had short letters delivered to the boys by divers. They gave a deadline of 9:00 am to clear out, setting off a frenzy of moving and packing.
No one in Mae Sai is prepared to think the worst, let alone say it aloud.
Professional cave divers from Europe are making the unsafe dives with a contingent of Thai navy SEALs.
News that some of the boys, especially the younger ones, are suffering from malnutrition, has added to those fears.
Elon Musk, the entrepreneur behind the Tesla automobile and the SpaceX rocket company, has said he would send engineers to help.
But it is the families of the children who feel these questions most keenly.
But Bew's parents were most concerned with their son's well-being. Second message reads, "I miss dad and mum, I think of you every day".
"They don't know us", he said. "Rescuers need to find an opening to the roof of the cave".
Officials announced earlier that oxygen levels inside the labyrinthine cavern system are now at 15 percent - down from a standard level of 21 percent - putting the kids at risk of hypoxia, which can be fatal. Don't worry about me too much.
"Tonight, more than likely we will be spending the night up there in the forest. We have limited amount of time". "Some [of the chimneys] are as deep as 400 meters. but they still can not find their location yet", he added.