Too often, air dryers are placed in hot environments where the ambient temperature and compressor discharge temperatures are high. This needs to be considered when you are sizing a dryer, so the unit has enough capacity to remove the water from the air.
The issue is the amount of moisture in the compressed air at elevated temperatures and the ability of the dryer, if a refrigerated unit, to expel the heat that is given off when moisture condenses from the airstream. The hotter the inlet air the more moisture it contains, every 20° in extra temperature doubles the amount of water vapor in the air. Thus, hotter air needs a dryer with a larger refrigeration circuit capacity, or in the case of desiccant dryer more desiccant beads.
If your air dryer is subject to ambient temperatures above 100° F, or the ambient air temperature is higher than 100° F during the hottest and most humid operating conditions, you likely need to upsize your dryer. Dryer manufacturers all have temperature derating tables in their dryer sales literature. Take heed or you will have moisture in your compressed air, causing trouble.
It should be noted that upsizing dryers has an additional benefit, less pressure drop. This may give your downstream machines and equipment more air pressure or allow you to drop your compressor discharge pressure. And if you purchase a cycling style refrigerated air dryer, or dew point controlled desiccant dryer, the units will reduce power or purge when the flow or moisture conditions are more reasonable.
