Need the jargon explained. We've asked the NSW Rural Fire Service what do fire danger ratings actually mean. How far can embers travel ahead of the fire? And, can a fire really create its own weather pattern?
Each year thousands of NSW RFS firefighters battle out-of-control blazes, they issue alerts to the community and they also talk about worse case scenarios.
Protecting lives is at the heart of each alert issued, each warning given and each call out, NSW RFS operational officer Brett Taylor said.
What do fire danger ratings really mean?
Ratings are calculated daily by the Bureau of Meteorology (BoM), not the NSW RFS.
"They look at what the predicted winds will be, the temperature, the relative humidity and the drought factor," Mr Taylor said.
"All of this combined gives you your fire danger rating."
Mr Taylor said the rating will give you an idea of how a fire will behave if one ignites on that day.
"It's giving people the knowledge so they can make a decision about enacting their Bushfire Survival Plan.
Because weather districts across NSW can be large, the BoM takes average readings across the entire area.
- LOW-MODERATE: Fires can be easily controlled and may spread up to 250 metres an hour. Make sure your Bushfire Survival Plan is up to date.
- HIGH: Fires can be controlled but still present a threat. Embers may be blown ahead of the fire and around homes, causing other fires to occur close to the main fire. Rates of spread up to 500 metres an hour are possible. Make sure your Bushfire Survival Plan is up to date.
- VERY HIGH: Fires can be difficult to control and present a very real threat. There may be ember attack up to two kilometres from the fire front and rates of spread up to 1km an hour. Review your Bushfire Survival Plan with your family.
- SEVERE: Fires will likely be uncontrollable, unpredictable and fast moving with flames that may be higher than roof tops. There may be ember attack up to 4km from the fire front and rates of over spread up to 1.5km an hour. Leaving early is the safest option for your survival. Well prepared homes that are actively defended can provide safety but only stay if you are physically and mentally prepared to defend in these conditions. If you're not prepared, leave early in the day.
- EXTREME: Fires can be uncontrollable, unpredictable and fast moving with flames in the tree tops and higher than roof tops. Thousands of embers will be blown up to 6km from the fire front, causing other fires to start and spread quickly ahead of the main fire. Rates of spread can be up to 2km an hour. Leaving early is the safest option for your survival. Leave early in the day if you are not prepared to the highest level such as if your home is specially designed, constructed or modified and situated to withstand a fire and you are well prepared and can actively defend it if a fire starts.
- CATASTROPHIC: Fires will likely be uncontrollable, unpredictable and very fast moving with highly aggressive flames extending high above tree tops and buildings. Thousands of embers will be blown violently into and around homes, causing other fires to start and spread quickly up to 10km ahead of the main fire with rates of spread up to 5km an hour. Ensure your survival is the primary consideration in any decision.The safest option is for you and your family to leave in the early morning of any day declared Catastrophic even the day before as soon as the rating is issued. Under no circumstances will it be safe to stay and defend.
What is a total fire ban?
High level fire danger ratings are often accompanied by a total fire ban.
"It's a combination of all four factors - temperatures, winds, relative humidity and drought factor," Mr Taylor said of why total fire bans are declared.
During a total fire ban day, bushfires are more likely to spread and cause damage due to the very hot, dry and windy conditions.
To reduce the risk of fires damaging or destroying life, property and the environment the NSW RFS Commissioner may declare a total fire ban.
During a total fire ban you cannot light, maintain or use a fire in the open, or to carry out any activity in the open that causes, or is likely to cause, a fire. More rules here.
When are emergency alerts issued?
These are issued when property is under threat.
"It's about telling people what they need to do - stay and defend [their property] or leave," Mr Taylor said.
"It's telling people they're being impacted by fire and they need to do something. It's all about saving people."
Ember attacks and spot fires
Strong winds and out-of-control fires can lead to embers flying in the air many kilometres ahead of the main fire front which can then start new fires (spot fires).
"With really strong winds you can have spot fires up to 5-10 kilometres ahead," Mr Taylor said.
"These usually happen with bushfires, grass fires don't spot so far."
Fires create their own weather patterns
Large bushfires can create their own weather patterns, with wind gusts and in bad cases lightning.
"A fire creates its own hot air, the air rises very quickly and it creates its own weather pattern, almost like a thunderstorm," Mr Taylor said.
"In extreme conditions, lightning can occur."
Should I stay or should I go?
This decision should be made now, before a fire is burning anywhere near your home.
"If you've made the decision to stay and defend then don't change that decision," Mr Taylor said.
"Your house is your safest place during a fire. It may catch on fire a little bit, but you'll be safer inside because modern houses burn slow and they're designed to withstand some fire.
"It gives you time for the main fire front to pass through and then you can go outside."
Where is your Neighbourhood Safer Place?
These are a place of last resort during a bushfire emergency.
"They're designed for rural and remote communities ... it's a place of reduced fuel load," Mr Taylor said.
"It's usually a big oval or open space like a school."
Stay up to date
Regular updates will also be provided on this website as well as your local radio station.
Call the Bushfire Information Line on 1800 NSW RFS - 1800 679 737.