Air coolers operate on the principle of evaporative cooling, where air is passed through water-saturated cooling pads to absorb heat and cool the air before it is released into the room. As the ambient temperature rises, the cooler's ability to cool the air becomes more effective. When the surrounding temperature is higher, there is a greater temperature differential between the warm air entering the cooler and the cool water inside the pads. This increased differential allows for more efficient heat absorption and, consequently, more noticeable cooling of the air. Essentially, the higher the temperature, the more effective the cooling process becomes, as the system is able to extract more heat from the incoming air. However, it is important to note that the cooling performance will start to plateau as the temperature reaches extremely high levels because there is a limit to how much heat the air cooler can remove from the air in such conditions.

Humidity plays a pivotal role in the efficiency of air coolers. The principle behind evaporative cooling relies on the evaporation of water, which cools the surrounding air. When humidity levels are high, the air is already saturated with moisture, reducing its capacity to absorb more water. As a result, the evaporation process slows down, and the air cooler’s ability to cool the air decreases. In high-humidity environments, air coolers may not perform as effectively, as the cooling pads will not evaporate water as efficiently. The reduction in evaporation means that the air cooler cannot effectively lower the temperature of the room. In contrast, in dry climates, where there is little moisture in the air, air coolers perform much more efficiently because the air has a higher capacity to absorb the moisture from the cooling pads, enhancing the cooling effect.

The interplay between temperature and humidity significantly affects air cooler performance. For optimal cooling, air coolers are most effective in regions where temperatures are high and humidity levels are low. Under these conditions, the process of evaporation works at its maximum efficiency, resulting in a significant drop in air temperature. However, in areas with high humidity, the cooler's performance can be compromised. Even if the temperature is high, the high moisture content in the air prevents efficient evaporation. As humidity increases, the cooler may struggle to achieve any meaningful temperature reduction, and the overall cooling effect may be minimal. In such climates, traditional air conditioning systems may offer a more effective solution, as they do not rely on evaporative cooling.

As the ambient temperature rises, the demand for air circulation increases to ensure the cooling effect is maintained. Many modern air coolers come with adjustable fan speeds, which help optimize airflow according to the temperature. Higher fan speeds enhance the cooling effect by increasing the volume of air passing through the wet cooling pads, which helps absorb more heat from the air. However, in high-humidity environments, increasing fan speed alone may not significantly improve the cooler's performance, as the key limitation is the evaporation rate.

Air coolers are more suitable for use in dry and arid climates. In regions with fluctuating weather patterns, users may need to adjust the settings of their air coolers or choose models specifically designed to handle varying humidity levels. Some air coolers are equipped with features such as humidity control or automatic adjustment of fan speeds to optimize performance in both dry and moderately humid conditions. In tropical or coastal regions, where humidity is consistently high, users may need to look for advanced air cooler models that are designed to operate effectively under these conditions, though the cooling results may not be as substantial as in drier climates.