Fall colour fallen flat? Blame it on the rain.

Gratuitous baby photo: Lila in the leaves, 6 months old.

The autumn colours are pretty spectacular in the Pacific Northwest this year (at least by PNW standards). Sure, normally we get a few weeks of pretty leaves, but it’s nothing compared to the show back east. Which made me wonder: what makes fall colours more vibrant from one year to another?

Autumn colours at Trout Lake, East Vancouver…

As I suspected, it’s all in the weather. Chlorophyll, the chemical compound that makes leaves appear green, disappears fastest during an autumn with dry, sunny days and cool nights, exposing the leaves’ orange and yellow pigments. Dry weather concentrates sugar production, which brings out the red.

…and on my back patio. (‘Fireglow’ Japanese maple.)

That explains it. We’ve had an uncharacteristically sunny, cold autumn. So next time we have our usual ho-hum fall colour? I’ll just blame it on the rain.



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