It was supposed to be a warm, sunny day.

We had slathered on the sunscreen and filled the Camelbaks up to capacity. The weather forecast said 68 and sunny throughout Marin.

But as we approached it, the bridge was wreathed in fog. And as we started up Mt. Tam to Pan Toll Ranger Station, the fog got thicker. And thicker. And then it started to drip rain in spurts. And the fog was so thick you could barely see 50 feet up the road.

At Pan Toll, the fog was still quite thick, but we weren’t about to waste our first day out hiking in months, so we put on all the layers we had brought (which wasn’t many) and set off down the Matt Davis trail – one of our favorites on Mt. Tam.


The rain started up again not far down the trail, but we stuck it out and learned something interesting about the Mt. Tam ecosystem.

Rainy-drySometimes it rains from the trees.

As soon as the trail left the woods for a stretch of grass, the rain was gone and the trail dry. Back into the trees, and the rain started up again.

In some places, there was even a very distinct line where the rain stopped.

It was like ducking out into a rainstorm and then back inside, except that it was raining “inside” instead of outside.

What’s actually happening is that the coastal trees condense the thick fog in their upper stories, and then the condensed water drips down as rain onto the understory and the ground (and the hikers).

So we occasionally had to run out of the cover to get away from the rain, but we managed to not get too wet.


And the fog had even started to lift by the time we reached our favorite lunch spot – Table Rock with a view of Stinson Beach.