On Wednesday afternoon, 44 fires were burning from Lapland in the far north to the southern island of Gotland.
Hot weather and persistent drought are the main causes, and the national weather service has issued fire warnings for almost the entire country.
Italy and Norway have both despatched firefighting aircraft to help.
Sweden said Italy had sent 13 people in two Canadair CL-415 "waterbombers", each of which can carry 6,000 litres of water at a time.
Norway's national broadcaster NRK, meanwhile, reported that 10 helicopters had been despatched to aid its neighbour - six on Tuesday and another four on Wednesday- despite the risk of similar fire outbreaks in Norway itself.
The wildfires have raged in parts for days and without a break in the hot dry weather they have shown little sign of stopping.
Many people have been evacuated from their homes in Sweden, while others have been told to shut off all ventilation to keep smoke outside.
Fire chief Britta Ramberg told Swedish media the fire in Jämtland was "the largest and spreading the fastest". Official advisories said that this blaze grew from 1,600 hectares to 3,000 on Tuesday alone, and that firefighters had been unable to contain it.
Many firefighters were being recalled from holiday to join the operation.
More about: Sweden
