Port Phillip is often warmer than the surrounding oceans and/or the land mass, particularly in spring and autumn; this can set up a "bay effect" similar to the "lake effect" seen in colder climates where showers are intensified leeward of the bay. Relatively narrow streams of heavy showers can often affect the same places (usually the eastern suburbs) for an extended period, while the rest of Melbourne and surrounds stays dry. Overall, Melbourne is, owing to the rain shadow of the Otway Ranges, nonetheless drier than average for southern Victoria. Within the city and surrounds, however, rainfall varies widely, from around 425 millimetres (17 in) at Little River to 1,250 millimetres (49 in) on the eastern fringe at Gembrook. Melbourne receives 48.6 clear days annually. Dewpoint temperatures in the summer range from 9.5 °C (49.1 °F) to 11.7 °C (53.1 °F).