A number of large bushfires have been burning in California during the last week, fuelled by strong winds and dry vegetation.

On the weekend, a fire located about 100km to the north of Sacramento claimed the lives of 29 people and destroyed more than 6,000 buildings. According to reports, this is California's deadliest and most destructive bushfire on record.

Further south, another fire burning near Malibu produced a frightening fire whirl on the weekend. Often referred to informally as a 'firenado', this phenomenon occurs when hot air rapidly rises above a fireground and cooler air rushes in from the sides to replace it. This causes a narrow column of air to start spinning violently, sucking in the smoke and flames around it. While fire whirls aren't as strong as tornados, they are still dangerous and can send debris and embers flying through the air.

Some of the fires burning over the weekend were exacerbated by the Santa Ana winds, which are a dry and gusty katabatic wind that blows down from the mountains towards the coast in California.

Unusually warm weather in recent months has also left vegetation exceptionally dry for this time of year in parts of California, particularly in the north. This is also likely to have contributed to the dealy bushfires in the last few days.