Extreme temperatures and high humidity can negatively affect the performance of a condenser microphone. Humidity problems generally manifest themselves as crackling and/or a loss in frequency response. Fortunately, most studios are air conditioned, which removes humidity from the air. Never store your microphones in a damp environment or allow a singer to put a humidifier in the vocal booth! Always keep a desiccant (small bag of silica) in the microphone case and be sure to maintain the dryness of the desiccant as required. If your condenser microphone has been in an extreme temperature (cold or hot), it’s always good to let it acclimate to room temperature before applying power.
Many classic studios would keep their condenser microphones in a hot box – a box with a light bulb generating a low level heat (like an incubator). If you are having humidity related problems, try putting your microphone near the heat of a light bulb for half an hour. Never use a blow dryer on your condenser microphone!