Solution
The specifications document for c-series chassis and other many NI hardware will describe their environmental conditions it can withstand in the section entitled "Environmental". For example the cRIO 9045 is tested up to 90% relative humidity non-condensing.
Example from the cRIO 9045 Specifications Document

For environments that exceed these conditions, there are a couple options:
1. Conformal Coating
Certain NI products can be purchased with conformal coating which will protect from condensation and other environmental factors. See
Conformal Coating and NI RIO Products a list of products that can be conformal coated and more information about this option.
2. Industrial Enclosure
The Industrial Enclosure for CompactRIO and CompactDAQ can protect a cRIO or cDAQ from environmental factors such as condensation. See the product page for exact specifications of this protection.
3. FieldDAQ
FieldDAQ is a rugged, water-resistant, and dust-proof data acquisition device suited for severe environments