The possibility of rainfall enhancement by asphalt ground coatings is analysed by means of observations of natural cloud formations over the small flat island of Anegada. Anegada is comparable in size to the contemplated artificial asphalt coatings and probably produces smaller effective differential heating. A case study using the Woods Hole instrumented aircraft data is made on a day in which the Anegada cloud street produced rain. Heated island theory is used to estimate the “equivalent heat mountain” and updraft associated with the island warming. These results are compared with the aircraft temperature and moisture cross sections and cloud maps made from time-lapse photographs. The study indicates that the asphalt coating method is sufficiently promising to warrant intensified investigation, for which specific means are suggested.