How you know it's no good to ride

I was walking home from the office today, and I noticed it had just started to drizzle out. Last night and this morning were below freezing, so the surface of the ground was clearly frozen. My typical tell - water puddles at intersection corners - indicated it was a risky day to begin with. But what really put the icing on the cake (almost literally) was the slightly warmer atmosphere, light rain cover, *and* frozen ground.

In fact, just to test things out, I tried scuffing the soles of my shoes in the middle of the street, while crossing at the crosswalk. Normally there's enough resistance to make me feel uncomfortable about ruining my shoes, but today the ground was as slick as ice. There was no grip whatsoever. Meanwhile, the sidewalks were still coarse enough to grip - I suspect this is because of the more porous concrete used on sidewalks throughout Manhattan. But I don't think I'll be riding around, sidewalk hopping any time soon.

Of course, the weather turned for the "worse" and the drizzle turned to rain in the late afternoon. After about an hour of rain, around 7pm, I tried my test again. The rain had thawed the ground surface enough to make scuffing possible - despite the rain. Lesson learned:

If it's warm enough to rain, and
It's been raining for at least an hour, and
The temperature is on its way up, ...

...then it's safe to ride in NYC.