A portable, evaporative air cooler ideal for off-road utility vehicles such as bulldozers, earth working equipment and the like. A corrosion-resistant, plastic housing comprises a rigid rectangular base and a rigid mating cover. The cover defines an air inlet, a fan intake plenum, and an air output. A fan mounted on the cover draws ambient air into the housing and outputs cooled, humidified air through an adjustable, louvered air distributor head adjustably positioned by the user. The distributor head may be coupled directly to the air output, or it may be remotely positioned with a flexible hose. The base defines a reservoir subdivided into an air admission compartment, an adjacent wick compartment, and a terminal filter compartment. Water within the reservoir partially fills all three compartments. The air admission compartment is covered by a prefilter grate that prescreens incoming particulate matter. The wick compartment seats a corrugated, absorbent wick having a plurality of air passageways. An anti-sloshing filter integrally projecting from the wick covers the filter compartment. Air drawn through the air inlet is screened through the grate, humidified and filtered. The cooled, humidified air is forced upwardly through the fan intake plenum and discharged through the distributor head into the application area. Cooled air from the output also cools the fan motor during operation.