The islands are tropical, but temperature varies a good deal with altitude. Coastal temperatures average around 27°c (81°f), but the mountain regions average only 20°c (68°f). Seasons are distinguished more by a change in precipitation than by a change in temperature. From October to May, the northern regions of São Tomé and Príncipe receive between 100 and 150 cm (40 to 60 in) of rain. The southern portions receive about 380 to 510 cm (150 to 200 in).