People with asthma and other respiratory conditions have been warned to prepare for potentially harmful, dusty conditions – even dust storms – across South Australia on Thursday.

The hot, windy weather in South Australia comes as Sydney is set to endure yet more rain on Thursday, having already had a month’s rain in just two days.

Parts of eastern NSW have had their heaviest rainfalls in up to three years this week. Weatherzone reports that Terrey Hills in Sydney had 85 millimetres of rain in the 24 hours to 9am on Wednesday – its best since 2016.

Richmond had 55.6 millimetres – its heaviest rain since June 2017 – while 65.6 millimetres at Observatory Hill was the city’s highest daily total since March. Sydney’s September average rain is 68 millimetres.

There has also reportedly been useful rain over some fire-affected areas in north-east NSW this week.

Cooler conditions & light rain have been welcome today. This map shows light rain over the major firegrounds. The Bees Nest Fire received the most rain but it was not sufficient to extinguish the blaze. #nswrfs #nswfires
Stay up to date: https://t.co/KiIzxOFlQZ pic.twitter.com/HC7Zr0eQj6

— NSW RFS (@NSWRFS) September 18, 2019

https://twitter.com/VaVeros/status/1174178257287163909

In South Australia, the weather bureau is forecasting strong winds between 50 and 70km/h for much of the state and central and western Victoria. Wind gusts might top 90km/h during the day.

The temperature in Adelaide is forecast to climb to an unseasonal 30 degrees on Thursday. The hot, windy weather means fire danger is also elevated across much of SA.

“There are large areas of the state that are very dry, and that could potentially produce fairly widespread areas of dust,” supervising meteorologist Matt Collopy said on Wednesday.

“That dust will sort of stream down with the northerly winds. Adelaide is probably not as likely to be affected as some areas but there’s certainly still the potential to see that dust here in Adelaide.”

SA Health acting chief medical officer Nicola Spurrier said the dust could cause flare-ups in people with known respiratory conditions, such as asthma, or cardiac problems.

“We’re recommending to people to really try to stay out of the dust,” she said.

“That’s staying inside their house with the windows up as much as possible, particularly these vulnerable groups.”

Heartbreaking scenes for our farmers at Cowell as dust storms batter the state's west coast. Report in 7NEWS at 4pm and 6pm. Send your weather photos or videos to 7NEWS Adelaide: https://t.co/3Q4z2KvMQ1 #7NEWS pic.twitter.com/fpDuJXtqjL

— 7NEWS Adelaide (@7NewsAdelaide) September 19, 2019

Dr Spurrier said people with diagnosed conditions should ensure they followed their management plans.

State Emergency Service chief of staff Darryl Wright said the forecast winds could bring down trees and affect driving conditions.

“Where possible, people should avoid being around large trees during strong winds, and secure loose items, such as trampolines,” he said.

With strong to gale force & gusty winds predicted across the state tomorrow, SAPOL are reminding road users to:

🚗 Drive to the conditions at all times;
🚗 Make sure you use your headlights if your visibility is obscured due to rain or dust;
🚗 Pull over & wait until it’s safe.

— South Australia Police (@SAPoliceNews) September 18, 2019

South Australia Police has also urged drivers to take care in the windy, dusty weather.

The dust is expected to settle in South Australia as a band of showers moves across the state on Thursday night and early on Friday morning. Five to 15 millimetres of rain is predicted for Adelaide on Thursday night.

Elsewhere, Melbourne is expecting a sunny maximum of 23 degrees, with north-easterly winds up to 45km/h. Brisbane can expect a top of 26 degrees, with light winds.

Hobart is aiming for 22 degrees, also with light winds. It will be chilly in Perth, with a top of 16 degrees, and showers likely on Thursday morning.

-with AAP