The changes, to come in on Wednesday, December 2, are set to coincide with the arrival of summer and the accompanying fire season.

Spokesperson for NSW RFS, Greg Allan, said that the changeover was part of a national overhaul of emergency warning systems.

"The updates are part of a nation-wide approach to emergencies and natural disasters, and are designed to bring all the states and territories under one system and make it easier for everyone to recognise the alert levels," he said.

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The changes will see existing alert icons change to yellow for "Fire Advice", orange for "Watch and Act", and red for "Emergency Warning".

Mr Allan said that while the colours are changing, the message remain the same.

"For each alert level the new colours will be consistent across NSW and its neighbouring states, along with the Northern Territory.

"What we ask is that all residents familiarise themselves with the new look but remember that the three levels or warning advice will remain the same.

Mr Allan said he also encouraged people to download the NSW RFS app or update their existing version.

"It is a handy tool to have and anyone who already has the app needs to update the app from tomorrow to make sure that it is functioning correctly and you see the new icons.

"We are expecting a busy fire season ahead with a lot of grass growing west of the Great Divide and contributing to high fuel loads, however we are concentrating on prevention and making sure any outbreaks are brought under control and contained swiftly."

The changes to the alert icons are the first step in an overhaul which will grow to include other disasters such as storms, floods and cyclones under a national banner known as the Australian Warning System.

The system has been designed based on feedback and research from across the country, and will use a nationally consistent set of icons to show warnings on both apps and websites.