View Full Version : Temperatures Underground

07-11-2015, 01:35 AM
So, a while ago, I did a blog post on Alligators in Sewers, and I came across an interesting tidbit that said the deep tunnels under New York maintain between 80 - 90 degrees year round. Now I'm working on an idea that's going to be set down there, and I want to double-check that.

Unfortunately, my google-fu is not strong and I can't find anything on it. The best I can get searching for underground temperatures is that the temperature of the Earth is a constant 55 - 60 degrees once you get about 5 feet down.

Does anyone know where I might look for confirmation of my initial info?

07-11-2015, 05:50 PM
Temperature under ground is 56 degrees F. It's a constant and varies slightly, but not much. Tunnels under NYC are also heated by steam so they stay warm.

What do you need for your story? There are geothermal vents in many states that alter the temperatures, geothermal wells often run in the 70's and sometimes higher than 100 F. Underground water sources can change temperature dynamics as well. Though it's darned hard to chill an area to lower than 56 F, you story could easily find a way to be above that.

The USGS has a lot of data on geothermal temperatures.


King Neptune
07-11-2015, 05:54 PM
The mine is so deep that temperatures in the mine can rise to life-threatening levels.


The deepest tunnels under any part of NYC are the new water tunnels, and they aren't deep wnough for temperatures to start rising, as is the case in the Tautona mine. If you want warm tunnels under NYC, then make up some that are 2 miles deep.

07-12-2015, 03:22 PM
I have once worked in the Kushiro coal mine in Hokkaido, Northern Japan. It was really hot on the deepest levels there, as in no-sleeves, towels-around-your-head hot.

Becky Black
07-13-2015, 12:48 PM
I know from my grandad who worked the deep coal mines of the North East of England that temperatures underground were very hot. Men worked in as few clothes as they could get away with.

The page: http://www.dmm.org.uk/colliery/w001.htm has a part about the average temperature in the Wearmouth pit being 78-80 degrees and sometimes as high as 89. That pit was 1700 feet below the surface at its deepest point.

It could depend on what's going on down there too. If it's just a cave or other kind of space, it has to be pretty deep before it starts getting hot. But if you have activity in there, people, machines etc, producing heat then the problem becomes getting rid of that heat. If they don't have efficient ways to getting that out of there, it's going to get hot. See this page on cooling on the London Underground for example.