Montenegro has appealed for international help to fight forest fires as neighbouring Croatia battles to stop flames reaching its second city, Split.
Fires have raged along the Adriatic coast for days, prompting dozens of tourists and residents to flee the Lustica peninsula in Montenegro.
A shopping centre in Split had to be evacuated as the flames grew nearer.
Government ministers have headed to Split for an emergency meeting.
President Kolinda Grabar Kitarevic cut short a visit to Austria because of the crisis. Strong northerly winds and weeks of hot temperatures have made the situation more acute.
The flames were whipped up by a storm late on Monday and some areas on the outskirts of Split were evacuated. Roads to the south of the city were reportedly cut off by the fires.
A waste dump was set alight and the army were called in to prevent a village from going up in flames. By late on Monday evening, the mayor said the worst was over but some suburbs to the south still appeared to be at risk.
Tourism officials in Croatia said no visitors to the region had been harmed and they expected the fires to be brought under full control as the winds decreased.
Further to the south on the Adriatic coast, in Montenegro, fires threatened the northern towns of Tivat and Herceg Novi and the flames had already reached the village of Durasevici.
Other countries in southern Europe are battling fierce fires too.
Fire broke out in a pine forest at Castelfusano, on the Italian coast south-west of Rome, and the smoke was visible from the beaches at Ostia.
In Portugal, a state of emergency was declared in an area in the east, a month after 64 people died in fires in the Pedrógão Grande region further north.
In the south of France, at Castagniers to the north of Nice, firefighters said they had prevented a fire from spreading after it had ravaged 120 hectares (300 acres) of forest.