Victorians are being warned a warm and sunny spring week ahead will bring with it a high pollen count and an extreme hay fever risk.
October was the wettest month on record for Victoria and maximum temperatures were below average for much of the state, according to the Bureau of Meteorology.
The state is now experiencing its first real taste of spring, with a top of 25 degrees Celsius forecast for Melbourne today, 27C and sunny tomorrow and 29C and mostly sunny on Wednesday.
But the combination of a wetter-than-average October and this week's hotter days mean a very high pollen count for much of the state, Melbourne Pollen Count researcher Edwin Lampugnani said.
Northerly winds are also expected to bring grass pollen from the north and west of the state to Melbourne.
"Up until now, the pollen count has been relatively low. In part, that's because we've had a lot of wet weather which has dampened down the amount of pollen in the air," Dr Lampugnani said.
"But all that extra moisture in the soil really means that the grass is going to be kicking on now that we have this warmer weather starting.
"So over the next week, we're expecting Melbourne to experience some pretty high pollen levels."
The Melbourne Pollen Count initiative, run by the University of Melbourne, tracks the grass pollen across the state and issues forecasts.
Those with hay fever would already be feeling the effects this month. Pollen levels were at "extreme" for the South West and Wimmera regions yesterday, and "high" for the rest of the state.
Wednesday is expected to be the worst day this week, with an "extreme" rating expected for the state.
La Niña weather event expected to drive pollen count
Australia has some of the worst hay fever rates in the world, and Melbourne and Canberra regularly jostle for the label of being the globe's worst city for allergies.
At least 15 per cent of Australia's population suffers from hay fever, or allergic rhinitis, with research suggesting that number is growing.
Janet Davies, allergy researcher at the Queensland University of Technology, told RN Breakfast that there had been a "step up" in the pollen count across the country in recent years.
"We're expecting, since the Bureau of Meteorology has predicted that this year will be another La Niña year — and we're seeing that to be borne out right now — that that's going to drive increased increased grass pollen loads in the air," Professor Davies said.
The Melbourne hay fever season, which officially runs from October 1 to December 31 each year, brings with it an increased risk of thunderstorm asthma.
Six years ago, Melbourne experienced the largest thunderstorm asthma event ever recorded, resulting in more than 3,500 emergency presentations, 35 ICU admissions and 10 deaths.
Asthma and immunology experts have warned Victorians to have a plan in place for any thunderstorm asthma events this season.
Dr Lampugnani said predicting what the rest of the season would look like was more difficult this year.
"November is traditionally one of the highest periods of the year for grass pollen. And that slows off towards December, so by about Christmas, usually most people have relief because those pollen levels will be low," he said.
"But this year, it's a little bit unusual, because we've had such a late start in the season.
"So we don't know what's going to happen as we roll around to December and Christmas time.
"We're hopeful that we'll snap back into normality and it'll be a nice low grass pollen count for Christmas."
