I have found during heavy rain associated with lightening interrupts the signal. I have it mounted on the roof of my house no more than 30 feet between the sensor and display. I get a great signal in other conditions.
Heavy rainfall and lightning can indeed cause brief interruption of signal; you may wish to try relocating the display unit to see if that helps with reception. Also, ensure you are using quality alkaline batteries such as Rayovac or Energizer in the units; avoid using heavy duty or rechargeable batteries. Should you require further assistance, just let us know. Have a great day!