Dec. 21, 2020
Today is day 82 of the 2020 grass pollen season and it's time to let you know how this season compares to past seasons.
It's day 82 because we count and forecast grass pollen daily from October 1 through to December 31, a total of 92 days.
Today's graph shows just what a season the 2020 grass pollen has been.
In our mid-season report we noted that the cumulative grass pollen count for 2020 was tracking above Melbourne's long-term average.
The cumulative grass pollen count is the daily sum of all the grass pollen caught in the trap since October 1.
The figure shows that trend continued and the 2020 season - that's the brown line - remains well above the long-term average, the dotted line.
2020 is a bigger season than last year’s season - the dark blue line - which was another above average season. In fact, it’s been more than 20 years since there’s been a season bigger than the 2020 season.
Another way of assessing 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 20 high days and 13 extreme grass pollen days.
In other words, since October 1 40% of the days have been either high or extreme grass pollen days.
So, if you've noticed your hay fever's been bad this year, that could be the reason.
Melbourne's grass pollen seasons usually start levelling off as we get towards the end of the year.
Unfortunately, that hasn’t happened so far this year, the cumulative curve is edging upwards and high or extreme grass pollen days remain possible.
The good news is that we’re forecasting only another four high and extreme days this season.
And Christmas is looking fine with a forecast of a low grass pollen day. Hopefully that means we can stop worrying about the grass pollen season and start enjoying the Festive Season.