"It's going to continue to rise, but we don't really know by how much," Bent Göransson, a hydrologist with metrological agency SMHI, told Dagens Nyheter (DN) in reference to current flood levels.
On Sunday night, SMHI issued class 3 warnings for "extremely" high rivers in Jönköping and Kalmar counties.
A class 3 warning is the most serious on SMHI's three-level scale, and indicates "very extreme weather" which can cause "great danger to the public and important societal functions".
The warnings were issued late Sunday after torrential downpours soaked parts of Småland with more than 113 milimetres of rain in less than 24 hours.
"There has been an incredible amount of water in a very short time," SMHI meteorologist Ida Sjöström told the TT news agency.
Following the heavy rainfall, water levels of the Silverån river, which flows into the Emån river in southern Sweden, rose more than two metres above normal.
In Jönköping, water levels remain high, but for now, the situation is under control according to local emergency services commander Tommy Rovholm.
"For the time being, things are calm. We're pumping water out of a few cellars of people who may have been out of town at the weekend and came home today to find water in their basements," he told the TT news agency on Monday morning.
While the sun was shining over rain-soaked Småland late Monday morning, SMHI doesn't expect the storm run-off to reach its high point until Tuesday or Wednesday.
"In some areas there is still a lot of water on roads, so we're urging people to be careful and respect road blocks," said Andreas Enberg of Hultsfred emergency services.
Flooding has also been reported further north and east in Tierp in Uppland County following Sunday's rain.
More than thirty homes have been affected and the police station and the municipal offices are also dealing with flooded cellars.
"This is clearly the worst storm-related case of cellar flooding that I've ever seen," said Roger Rodin, head of water and sewage in Tierp, to Sveriges Radio (SR).
According to SMHI, more stormy weather is on the way, although the worst affected in Småland won't have to deal with any more rain on Monday.
"There is going to be more rain further north in Dalarna and Gävleborg counties," meteorologist Sandra Andersson told TT.
But on Tuesday, additional thunderstorms and potential heavy rains are expected to move across south central Sweden once again.