Nov. 20, 2020
As we're now 50 days in and well passed the season's midway mark, it's time to let you know how things are progressing.
Here at Melbourne Pollen, we measure how much grass pollen is in the air and make a 7-day forecast every day from October 1 through to December 31.
That's 92 days or roughly 14 weeks of counting and forecasting.
In September, we had a look at the season ahead and forecast that 2020 would be an average grass pollen season.
But we cautioned that the Bureau of Meteorology’s forecast for a La Nina year could change this, with good finishing spring rains having the potential to further boost grass growth.
A wetter-than-average October seems to have delivered that extra growth.
One way to assess the season is to look at how many high and extreme days we've had.
A high day is one when the average daily concentration of grass pollen is 50 grains or more per cubic metre of air, and an extreme day is one when there's 100 grass pollen grains or more.
High and extreme days are our worst days for hay fever and asthma.
An average Melbourne season has 12 high and 8 extreme grass pollen days. So far this season, we've had eight high days and nine extreme grass pollen days.
So, that's looking like 2020 will be an above average grass pollen season.
Another way of tracking the season is to plot the cumulative grass pollen count since October 1. That’s what we show in today's graph.
The current season is the red line and the long-term Melbourne average is the blue line.
The dashed lines show 1993, our heaviest grass pollen season, and 2015, our mildest season.
We’ve also included the 2012 season, as 2012 was Australia’s last significant La Nina event.
As you can see, the cumulative count for 2020 is currently above Melbourne's long-term average and even above the 1993 season.
And it’s not that far off the 2012 La Nina season.
But we’re still expecting the season will level off towards Christmas, as it does in an average season and as it did in the 2012 La Nina season.
We’re not expecting it will ramp up, as it did in 1993.
That said, we’re not done with 2020 yet. In fact, a new and experimental forecast model we’ve developed predicts that Melbourne will experience another eight high and seven extreme grass pollen days over the remainder of the season.
We’ll see how good that prediction is in our end-of-year season wrap up.