Australians were promised a dry summer, but many regions have been left dripping in humidity, leading to unsightly growth in some homes.

Heatwave conditions throughout January have seen temperatures exceed 40 degrees in several areas, in many cases made worse by moisture in the air.

Bureau of Meteorology senior meteorologist Dean Narramore said while Western Australia, southern parts of the Northern Territory and much of South Australia have had their expected dry summer, it has been a different story on the east coast.

The disparity is largely due to the winds coming from warming ocean areas.

“We’ve had high-pressure systems well south of the country, even south of Tasmania. What that means is the entire country will be experiencing easterly winds, so a wind coming from the east and moving across the country,” Narramore said.

“Where those winds are coming from, both the Tasman and the Coral Sea, the sea surface temperatures are one to three degrees above average over the last couple of months. So that means there’s even more moisture in the atmosphere as well.

“A prolonged period of easterly winds combined with warmer-than-average sea surface temperatures has led to a very humid and, at times, quite wet summer so far across eastern parts of the country.”

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Long weekend heatwave

Hot conditions are expected to continue over the upcoming Australia Day long weekend.

“Severe to locally extreme” temperatures are expected to extend to eastern NSW later this week, with high 30 to low-40-degree days up to 10 degrees above the average for this time of year.

Further inland, it will be even hotter, with parts of northern SA, south-west Queensland and north-western NSW expecting to sweat through temperatures in the mid- to high-40s.

The Queensland town of Birdsville will be among the worst-affected areas, with a forecast of 49 degrees on Thursday.

Narramore said fortunately, the looming heatwave was expected to be a drier heat than seen recently.

“Pretty much any time we get a prolonged period of easterlies, we’re likely to see that humidity return,” he said.

“But in the short term, to finish January into early February, it looks like we’re going to continue more of this dry heat across large parts of the country.”

Although the change will be a relief from recent humidity for many Australians, the damage may already be done.

Humidity significantly increases the chance of mould and damp in homes.

But if you’ve caught it early, or are just keen to take preventative measures, consumer group Choice household expert Chris Barnes said there are easy things you can do:

• Keep air flowing: Good ventilation can help prevent humidity and minimise moisture and mould growth. Open your home to air it out when it’s mild and dry outside;
• Line dry clothes: Barnes said simply hanging laundry to dry outside will significantly reduce moisture build-up in a home. “Drying your clothes indoors adds to the humidity, and if you use a dryer, it also adds to your electricity costs,” he said;
• Stay clean and tidy: “Mould needs organic matter to feed on, such as dead skin cells, dust or pet hair. By vacuuming and dusting regularly, you’ll minimise mould growth,” Barnes said;
• Use appliances that help prevent and manage damp and mould: Investing in a dehumidifier could be useful for a persistent damp or mould problem, as they remove moisture from the air. Barnes said refrigerant dehumidifiers were best for hot, humid conditions, while desiccant dehumidifiers were better suited to cold, damp conditions. For those who can afford it, keeping air-conditioning running for a while could also help, as many have specific dehumidify or ‘dry’ modes. Meanwhile, ceiling fans circulate air, which can help keep mould at bay. For targeting a specific area that needs ventilation, pedestal fans were handy and had low running costs, Barnes said.