Mid-season update

Nov. 29, 2013

How is 2013 going?

Based on the date of the season's first high grass pollen day, on October 21, I said we could expect about 25 high and extreme grass pollen days by December 31. A high day is one with an average of 50 or more grass pollen grains per cubic metre of air and our extreme days occur when the count is over 100.

So far this season there have been nine high days and one extreme grass pollen day. By the same time last year there had been ten high and six extreme pollen days.

The dotted line in today's graph shows the average daily grass pollen count from 1996 onwards. November is clearly our worst month with the daily count mostly in the red zone (high and extreme). The solid line is this year's count and it's mostly in the blue low zone.

Thanks to good winter and spring rains, it's been a good season for grass growth. The question is, why hasn't it been a far worse hay fever season?

It's no secret that November has been pretty cool. And in Melbourne that means southerly winds.

The pastures where our grass pollen mostly comes from are to our north and west. Carrying that grass pollen into Melbourne needs warmer north/north-westerly winds. So we've had the wrong sorts of wind this year for a bad hay fever season.

The other thing today's graph shows is that the season really starts to tail off in December.

With luck it'll all be over by Christmas.

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