See How Sweltering NYC's Busiest Subway Stations Get

NEW YORK, NY — Any straphanger knows New York City heat can feel even more oppressive on subway platforms than above ground. But it turns out temperatures at some of the city's busiest stations can reach potentially dangerous levels, according to the Regional Plan Association.

The influential planning group sent staffers out to test temperatures at 19 subway stops — including the system's 10 busiest — on Thursday, Aug. 9.

The outdoor high that day was slightly above normal at 86 degrees, but the platforms were nearly nine degrees hotter with an average temperature of 94.6 degrees, the RPA found.

Unlucky commuters waiting for a downtown 4, 5 or 6 train at Union Square faced a sweltering temperature of 104 degrees at 1 p.m., the highest reading the RPA got.

The only other spots to break 100 were the downtown 4/5/6 platform at Brooklyn Bridge-City Hall (102 degrees at 10 a.m.) and the uptown 1 platform at 59th Street-Columbus Circle (101 degrees just before 11 a.m.).

Temperatures that high could be harmful — the city's Department of Health warns that a heat index above 95 degrees is "especially dangerous" for older adults and other vulnerable people.

The A, C and E platform at 34th Street-Penn Station was the only place where the underground temperature matched the actual above-ground high, according to the RPA's readings. All but five platforms the group measured broke 90 degrees.

"The heat in underground subway stations isn’t just a nuisance for New Yorkers, but it also poses a serious health risk for those who not only ride the subways, but work on them too," the RPA wrote in a Friday article.

Patch reporters found similarly sweltering temperatures when they took to the platforms last year. The highest reading they got was 95.9 degrees on the 4/5 platform at Atlantic Terminal in Brooklyn.

Here are the hottest platforms at the 10 busiest subway stations, according to the RPA's readings from Thursday.

1. 14 Street-Union Sq, 104 degrees at 1 p.m., 4/5/6 Downtown platform
2. 59 Street-Columbus Circle, 101 degrees at 10:55 a.m., 1 Uptown platform
3. 34 Street-Herald Square, 99 degrees at 9:10 a.m., R/W Downtown platform
4. 34 Street-Penn Station (2/3), 99 degrees at 8:45 a.m., 2/3 Express platform
5. Times Sq-42 Street, 98 degreest at 10:45 a.m., 1/2/3 Uptown platform
6. 47-50 Streets-Rockefeller Center, 98 degrees at 9:30 a.m., BDFM Downtown platform
7. 14 Street-Union Square, 96 degrees at 1 p.m., 4/5/6 Uptown platform
8. Grand Central-42 Street, 94 degrees at 1:10 p.m., 4/5/6 Uptown platform
9. 34 Street-Herald Square, 94 degrees at 9:08 a.m., N/Q Downtown platform
10. 34 Street-Herald Square, 93 degrees at 8:59 a.m., R/W Uptown platform
11. Grand Central-42 Street, 92 degrees at 12:45 p.m., 4/5/6 Downtown platform
12. Fulton Street, 90 degrees at 9:20 a.m., J/Z platform
13. 34 Street-Herald Square, 89 degrees at 9:02 a.m., B/D Uptown platform
14. 34 Street-Herald Square, 88 degrees at 9:05 a.m., F/M Downtown platform
15. Lexington Avenue-53 Street, 88 degrees at 9:36 a.m., E platform
16. 34 St-Penn Station (A/C/E), 86 degrees at 9:25 a.m., A/C/E platform

(Lead image: Photo by Maria Cormack-Pitts/Patch)