A rain sensor is described comprising a tray (1) for the collection of rain water provided on top with evaporation and overflow side windows (4, 22) covered by a perforated cover (5). A finned float (9) is housed in said tray (1) so as to be able to move vertically as a function of the level of the water present in the tray. A permanent magnet (15) supported by said float (9) cooperates with an electric magneto-sensitive switch (16) that is fixed to the tray (1) in order to switch it between a first and a second electric state as a function of the vertical position of the float (9). <；IMAGE>；
