Yes, evaporative coolers can work in high humidity. Evaporative coolers work by evaporating water to cool the air, and the higher the humidity, the more efficient the cooling process. However, the effectiveness of the cooling process is limited by the amount of water available. In high humidity, the air is already saturated with moisture, so the evaporative cooler will not be able to cool the air as much as it would in lower humidity. Additionally, evaporative coolers are not suitable for areas with high levels of dust and other airborne particles, as these particles can clog the system and reduce its efficiency.