John and Carolyn Butko were travelling through bushfire affected communities to support the towns on Saturday.

Mr Butko said their four-wheel-drive was forced to stop at Brown Mountain, on the Snowy Mountain Highway, after the boulders slid onto the road.

Their vehicle was one of the first at the scene after the rocks rolled about 3.30pm on Saturday.

"They were two huge boulders, right in the middle of the road," he said.

"They were massive.

"It probably caused a fair bit of damage to the road."

The incident caused lengthy diversions for the pair.

"They've had heavy rain," Mr Butko said of the area.

"They didn't have fires there but it has been very wet.

"We were hoping to get to Sydney but we had to go on the back roads."

The road reopened on Sunday afternoon.

The impact damaged guardrails on the side of the road.

Mr Butko said the boulders were so big, they would have smashed through gumtrees on the other side of the road.

"We had to turn right back and head along a few other roads to get to Eden," Mr Butko said.

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The detours were further hampered by road closures following recent bushfires.

Mr Butko said the couple had been travelling through towns impacted by the recent bushfires to support the communities.

He said their journey to Eden took 12 hours after they diverted through Corryong.

The incident occurred after heavy recent rainfall in the region.

The nearby town of Bega has recorded 145 millimetres of rain this month, including 80 millimetres last Monday.

Fire impacted towns in the North East and southern NSW have had a reprieve in recent days through rainfall.

There was 10 millimetres of rain recorded at Albury Airport on Wednesday.

A total of 22.4 millimetres of rain has been recorded in Albury this month.

Scattered thunderstorms are also forecast on Tuesday.

The Bureau of Meteorology forecasts possible rainfall of three to 10 millimetres later in the day.