Crews mopping up in remote and rugged forests in Namadgi National Park after lightning strikes ignited three outbreaks on Saturday night and on Sunday are likely to continue work for days.

RFS crews were heading to the scene of the latest fire in remote bushland near Rendezvous Creek on Sunday night.

ACT RFS Chief Officer Andrew Stark said firefighters would have to work hard to contain the bushfire on Monday.

ACT deputy chief fire officer Michael Joyce said Tuesday was likely to be dangerous with the wind forecast to increase to up to 45 km/h and a maximum temperature of 38 degrees.

''The fire danger is likely to be a total fire ban and severe fire danger rating,'' he said.

''Humidity is going to be 20 per cent, but with those winds it boosts up the fire danger significantly.''

The first fire started about 11pm on Saturday near Sentry Box Mountain, near the ACT and NSW border, and the second near Mount Ginini, in the west of the park, at 2.30pm on Sunday. The fires were still burning on Sunday night but containment lines had been established.

Firefighters were working through the night at Mount Ginini and crews will fly back in to Mount Sentry Box Monday, where firefighters are being winched in and out.

Mr Joyce said the Mount Ginini fire was first seen by an off-duty police officer at Uriarra.

''If you see any fire and there are no fire trucks about, ring triple-0, and don't waste time,'' he said.

By mid-morning on Sunday the Sentry Box fire had burnt four hectares. Near Mount Ginini about 25 hectares had been burnt. Neither fire posed a risk of significant property damage.

At Mount Ginini, 35 firefighters and six heavy tankers were joined by a bulldozer. Two helicopters water-bombed across the rugged country.

The area of bushland had previously been burnt during the January 2003 firestorm.

Earlier, two remote area fire-fighting teams and two helicopters water-bombing attacked the Sentry Box fire, which had escaped the big fires of 2003.

Mr Joyce said fire crews were thankful the wind was not too strong.

''But the fires are pretty much moving slowly, if we can get onto them quickly today,'' Mr Joyce said on Sunday. ''We are fortunate there is not going to be much wind today.

''If need be, we will put in crews overnight and do backburning.''

While the fires would reduce fuel, Mr Joyce said the goal was to contain them to the smallest possible size.

''The main thing we do these days is put the things out. We can't risk them taking off.

''Particularly as here we are 10 years from 2003 and we have lightning strikes in the Brindabellas that caused those fires.''

''Having said that, there are still a lot of crews available within the city area. We have all our volunteer brigades and all the (Territory and Municipal Services) brigade on a high level of readiness and they will be in the next few days.''

The storm on Saturday evening struck Canberra's south hardest, throwing trees and branches across

roads and paths. A pergola at Banks was badly damaged. And storms on Sunday night brought 15 calls to the ACT SES for help with minor damage, mostly in the West Belconnen area.

NSW Rural Fire Service volunteers also fought about 70 blazes across NSW on Sunday.

Grass fires were burning in Stuart Town, near Wellington, and Numeralla, east of Cooma.

And firefighters in Victoria are getting on top of a major blaze burning in the south-west. The huge blaze at Kentbruck, which began in a pine plantation, has burned over 2700 hectares and smoke haze is visible throughout western Victoria.

with Lisa Cox and AAP