Diurnal and seasonal variations in the lunar tide of f0F2 are determined by analyzing hourly values for 2 years from several stations mostly at American longitudes. A phase advance of 3 or 4 hours from day to night is found at Huancayo in agreement with electric field measurements. Seasonal changes in the lunar tide of f0F2 are similar to those in ΔH at nearby stations. An unexplained solar cycle variation is found at Concepcion (25¿S geomagnetic).