Melbourne’s grass pollen season is fast approaching. While we’re not expecting much grass pollen in the air until late October, the outlook currently is for an average season.
Maps showing soil moisture levels (left) and satellite images of vegetation greenness (right). Images provided by the Bureau of Meteorology and NASA/USGS.
Melbourne's on-track for an average grass pollen season in 2020. This means we're expecting the season will be milder than in 2019 with fewer of the high and extreme grass pollen days that are the bad days for people with asthma or hay fever triggered by grass pollen.
In the 2019 season, Melbourne had 27 high or extreme grass pollen days and in an average season there are around 20.
To see what’s driving this outlook, we first need to review current conditions.
Rainfall in late summer and autumn across much of Victoria was well above average.
Melbourne, for instance, has already had 90% of its average annual rainfall of 650 mm.
It was shaping up to be a wet year.
But after the wet start, winter rainfall has been below average or very much below average across much of western and central Victoria. Pasture grasslands in these areas are the source of Melbourne’s grass pollen.
Today's first map shows moisture levels in Victoria's soils. This is the amount of water available to plants and is a major factor determining grass growth.
Brown areas in the map show below average soil moisture levels and grey areas soils with average moisture levels. Soils across much of the state are generally drier than at the same time in 2019.
Drier soils should translate into less grass growth this year and that should mean less grass pollen as well.
The next set of maps are satellite images from August 2019 and 2020. Grasslands in western and central Victoria are notable less green this year than last.
There's still a chance for good finishing spring rains to further boost grass growth and bring about a bigger grass pollen season. But the window where this can happen is narrowing.
That said, because the Bureau's current seasonal outlook for September to November indicates wetter-than-average conditions for the eastern half of Australia, we'll need to keep a close watch on that one.
Although the outlook is for an average grass pollen season, it’s important to remember that people with asthma and hay fever will still be at risk of epidemic thunderstorm asthma. Having good control of your asthma and hay fever will mean you’ll feel better and also reduce your risk of thunderstorm asthma.
People with hay fever should follow their hay fever treatment plan (or see their GP or pharmacist to get a plan if they don’t already have one), learn asthma first aid and have asthma reliever medication suitably available during the grass pollen season.
And, of course, visit us regularly to keep track of the daily grass pollen count and the pollen and thunderstorm asthma forecasts during the season.
People with hay fever should also remember that symptoms such as wheezing, breathlessness, chest tightness and a continuous cough are not related to hay fever and may mean you also have asthma. These symptoms may come and go or you might not have all of them. But it’s important to talk to your doctor and get it checked out.
People with asthma should ensure they have an up-to-date asthma action plan, take any preventer medication as prescribed, and always carry their asthma reliever puffer with them. If people with asthma develop asthma symptoms, they should follow their asthma action plan, or if they don’t have one yet, follow the 4 steps of asthma first aid.