An update on Victoria’s grass pollen season

Dec. 14, 2022

What's the 2022 Victorian grass pollen season look like?

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A couple of weeks ago, at the end of spring, we looked at Melbourne’s grass pollen season and noted that, despite this being the third La Nina event in a row, so far we've had a close-to-average season.

To the end of November, Melbourne had seen 11 high or extreme grass pollen days. These are the worst days for people with hay fever and asthma.

As of today, that tally stands at 17 (12 high and five extreme), which is close to Melbourne’s average of 12 high and 8 extreme grass pollen days per season.

Despite the continuing cool weather, we're still expecting to see a few more of high and extreme days in the run up to Christmas.

Today’s figure is a snapshot of the 2022 Victorian grass pollen season, with cumulative curves for Melbourne and three other monitoring sites – Churchill in Gippsland, Dookie near Shepperton, and Geelong.

The cumulative curves are obtained by adding the daily grass pollen level at a site to the sum of all previous daily values from October 1.

Each plot also shows cumulative curves for 2020 and 2021, which like 2022 were also La Nina years.

The current season in dark blue, the 2021 season in green and the 2020 season in red.

The dotted line shows the average of all recorded grass pollen seasons at each site.

So, what do the plots show?

First, 2022 has seen an average grass pollen season across the southern part of the Victoria (Churchill, Geelong and Melbourne) with only Dookie in the north of the state seeing above average levels.

This is likely because, as well as being wet, November and December have also been cool months with maximum temperatures that are well below average.

Second, while the extra rainfall a La Nina event delivers is obviously good for grass growth, only about half the time does that growth turn into a bigger grass pollen season.

Churchill and Geelong, for instance, have seen above average grass pollen levels in only one of the past three La Nina years. Dookie and Melbourne have seen two above average seasons in the last three years. At none of the sites have all three seasons seen above average grass pollen levels.

High rainfall is certainly no guarantee of a bad grass pollen season.

Meanwhile, to the north of us, La Nina has delivered Canberra its worst grass pollen season on record with the city so far having experienced more than 30 extreme days since October 1.

Download the Melbourne Pollen app to stay up-to-date with the latest Victorian pollen forecasts.

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