The Bureau of Meteorology has issued a severe fire weather warning for the ACT on Saturday.

Strong wind gusts of up to 45km/h are set to hit elevated areas on the fireground and winds are set to pick up across the ACT late morning, BOM meteorologist Gabrielle Woodhouse said.

"In Canberra city itself we will see winds increasing from about 10 or 11am in the morning," Ms Woodhouse said.

The Orroral Valley fire was downgraded to a "Watch and Act" level bushfire warning at 1.23am on Saturday, however an ESA spokesperson warned conditions were changing and could get worse.

People living near Tharwa Village, Boboyan Road, Apollo Road, Top Naas Road and Nass Road need to remain vigilant. Those living in Tharwa, Banks, Gordon and Condor should also monitor conditions closely and be ready to act.

Northwesterly winds in the afternoon, along with hot temperatures will be when the fire danger is at its highest.

These winds will fan the fire east towards Tharwa and Michelago. This will also edge the fire closer towards southern Canberra suburbs.

"Across the afternoon we are looking at north-westerly winds and they will be 20 to about 35 km/h across the ACT, for the higher parts in the south more around that 30 to 45km/h mark but again still from the west to north-westerly," Ms Woodhouse said.

"[On Saturday] we will see temperatures increasing relatively quickly through the morning and then persisting to be very very warm in the afternoon."

Road closures were also altered on Friday evening:

READ MORE - WHAT YOU NEED TO KNOW AS OF 7AM SATURDAY:

Canberra is forecast to reach a maximum of 41 degrees on Saturday. Smoke haze will remain persistent in the ACT on Saturday.

While the temperature will drop on Sunday there is a possible chance for a thunderstorm with wind gusts of up to 90km/h, which would elevate fire conditions.

Sunday is set for a maximum of 35 degrees but Ms Woodhouse said the thunderstorm would create erratic conditions.

"It's most likely from the late morning to early afternoon that the main risk period is," she said.

"Those thunderstorms have the potential to become severe and the main phenomena with those storms would be the potential for some damaging winds.

"It may bring a brief burst of rain and more windy and erratic conditions due to the wind gusts from the thunderstorms and that poses extra challenges around the firegrounds."

After Sunday, conditions are set to ease.

"It's a long weekend for people and not the nice kind of a long weekend ... it's going to be quite challenging," Ms Woodhouse said.

The ACT Emergency Services Agency also has a severe fire danger rating in place for Saturday.

The ESA extended its total fire ban until Sunday. A total fire ban has been in place in the ACT since Monday.

"All ACT residents are urged to review their bushfire survival plan or if you don't have a plan in place, to take the time to create one," an ESA statement said.

Conditions on Saturday are forecast to be similar to those in the 2003 bushfires.