A system to provide advance warning of the risk of local lightning on the basis of observations of local atmospheric electric field, radio noise at 27kHz and lightning impulse signal activity (2-200kHz). Combinations of measurements of these three parameters provide two levels of warning to enable action to be taken to protect personnel and equipment. The system comprises a sensing head unit (with proprietary operational health monitoring facilities - as JCI 133), a mounting pole acting as an antenna, a Base Unit with computer to provide power supplies and to control, analyse, display and record observations, an uninterruptible power supply unit and 100m cable for connecting the head unit to the Base Unit..