Weather and the Street Grid

The National Weather Service has issued another heat advisory for several upcoming days in New York City. Right now, they are reporting that it’s 87 degrees, but feels like 93.

Lately I’ve been noticing quite regularly that my car and the bank that displays the temperature nearby are routinely recording temperatures higher than those being reported. It appears the weather services are using Central Park as their baseline.

But most of Manhattan is not park, and most of the parks are not Central Park, but much smaller public spaces, many of them with significant percentages devoted to paths, basketball courts, and other things that soak up heat. Next City estimates 15 percent of the borough is parkland, and 36 percent streets, which presumably includes sidewalks. Several years ago, Newsweek wrote about a study stuggesting 20 percent of Manhattan is yard space — but much of that is also paved. That leaves about 30 percent of the city’s surface covered by buildings.

In other words, a large majority of Manhattan is paved or covered in buildings.

Which means in a large majority of the city, the temperature is going to be higher than it is in Central Park. Earlier today, the weather stations were reporting a temperature of 91 with a heat index of 100. But at Apple Bank in my neighborhood, the sign said it was 100 degrees. What’s the heat index in that case?

And what are the implications and consequences of consistent underreporting of daytime and probably also nighttime temperatures in Manhattan and other heavily urbanized areas?

It turns out that large portions of Brooklyn and much of the Bronx, areas with waste transfer stations and industry that also house populations that are mostly people of color, are even more vulnerable to high heat than most of Manhattan.

I have no idea if the temperature reporting discrepancies are enough, given the relatively small land area of New York and other cities in comparison to surrounding areas, to affect our understanding of the severity of climate change.

But the effects on individuals would be significant. If the weather services is saying the heat index is 101, based on conditions in Central Park, but its actually several degrees higher in much of the city, then that alone is putting people in danger. Given that hundreds of people die of heat-related problems in New York City every year, and that people of color are disproportionatly effected, I think it’s time the weather services reported temperatures in the neighborhoods people actually live in, not idealized conditions in Central Park.