[dangus]

Dry bulb temperature can reach the 80s. I’m presuming wet-bulb temperatures would be much lower because it’s so dry... but I’ve never measured them.

[Boiler Plate]

The amount of cooling you would get is dependent on the wet bulb as it indicates how much moisture the air can absorb before it saturates. Getting the relative humidity can allow you to figure it out as well.

Having said that, evaporative coolers work well in relative humidity ranges of 20%. I doubt it's that dry. I wonder if you are getting any close to the required outside air.

Where on the east coast are you and what are you thinking of using for your evaporative cooling system?