Abstract: An improved snow and sleet detector having a pair of substantially parallel detector screens spaced one below the other, the upper screen being open to the ambient. A rim is included which is highly thermally conductive and electrically conductive and encompassing the upper screen proximate the edges thereof. A thermostatically controlled heater is mounted in intimate thermal and electrical contact with the rim for maintaining the rim and detector screens at a temperature high enough to melt snow or sleet falling thereon. Circuiting is described for providing an electrical indication when the detector screens are conductively coupled by melting snow or sleet.