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 cRIO or cDAQ hardware 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