Firefighters continue to battle a bushfire in an Adelaide Hills conservation park, but it poses no immediate threat to houses in the area.

Key points: The fire is burning in the Black Hill Conservation Park at Paracombe

The fire is burning in the Black Hill Conservation Park at Paracombe A watch and act message has been issued for Paracombe, Athelstone, Castambul and Montacute

A watch and act message has been issued for Paracombe, Athelstone, Castambul and Montacute The CFS is concerned about the fire spreading as the temperature rises during the day

The fire in Black Hill Conservation Park began overnight and has forced the closure of Gorge Road.

About 50 firefighters are still trying to control the blaze which is burning in "very steep and difficult terrain".

An advice message is current for Paracombe, Athelstone, Castambul and Montacute.

The fire has burned through more than 60 hectares and the CFS earlier advised residents in the area to follow their bushfire survival plans.

"Given it's an uncontrolled fire, there are some properties, not directly under threat at this stage, however, we are asking people to put their bushfire survival plan into place," spokesperson Alison Martin said.

Hot northerly winds were a concern for firefighters

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The Bureau of Meteorology has issued fire weather warnings for the Mid North and Mount Lofty Ranges, where the threat level has been rated as severe.

"We're also seeing a strength in our northerly winds. We had unseasonally warm weather yesterday and that continued overnight," forecaster Jenny Horvat said.

"It looks like there could be some April record minimum temperatures broken.

"We're working very hard with the CFS to keep them up to date with those wind changes."

Former mayor of Adelaide Hills Council Bill Spragg, who lives near the Montacute quarry, said his property was close to the fire ground.

"We've been able to smell smoke for a number of hours now," he said.

"The fire has actually burnt into private property, there's a bit of farm land there, but the quarry is going to be a bit of a physical barrier which we hope will stop it."

Road closures are in place around the scene of the fire. ( ABC News: Matthew Smith )

"We've had a few small showers — not enough to dampen the activity of the fire.

"A number of people have already chosen to leave but there are a number of people who have stayed to defend their places."

Meanwhile, a bushfire that threatened homes near Clare in the mid north yesterday has been contained.

Firefighters remained at the scene overnight.

The CFS has urged anyone in the area to prepare a bushfire survival plan. ( ABC News )

The CFS said early reports suggested the cause of the fire was a burn-off which went out of control.

Another fire on the old grounds of the Strathmont Centre on Grand Junction Road in Adelaide's north is believed to have been deliberately lit.

Four people have been taken to hospital because of smoke inhalation.

Emergency crews were called to the scene about 3:15am.

It took almost 50 Metropolitan Fire Service personnel as well as CFS crews about 90 minutes to bring the fire under control.

The MFS said the blaze spread to nearby homes, causing damage to the room of a house.

"Brush fences and gardens of three other homes in Emmett Place were also damaged by the fire," police said.