An online campaign led by comedian Celeste Barber to raise money for volunteer firefighters has raised more than $18 million.

More than 410,000 people from around the world have pledged millions of dollars to the NSW Rural Fire Service in two days after Barber’s plea for donations, "Please help anyway you can. This is terrifying", was posted on social media.

Barber posted images of her mother-in-law’s house at Eden on the NSW South Coast on Friday, with the sky turned orange by the bushfires, and the words: "It's terrifying. They are scared. They need your help."

Her family were later evacuated. Facebook users from as far afield as Norway, United Kingdom, United States, Canada and the Czech Republic responded to Barber's fundraising campaign with donations.