in USDA hardiness zone 7a. Consequently, many subtropical indicator plant species typically found in more southerly latitudes are grown there, including Camellias, Ilex opaca, Magnolia grandiflora and Albizia julibrissin. However, Cape Cod falls below the threshold, as the warmest month, July, averages around . Therefore, the climate may be better characterized as either a maritime climate or a humid continental climate (particularly on the northern coast of the upper and mid cape, which is somewhat sheltered from the cooler onshore wind to the south). Precipitation on Cape Cod and the islands of Martha's Vineyard and Nantucket is the lowest in the southern New England region, averaging slightly less than a year (most parts of New England average ). This is due to the maritime influence inhibiting summertime thunderstorm development and maintenance. The region does not experience a greater number of sunny days, however, as the number of cloudy days is the same as inland locales, in addition to increased fog. On average, roughly of snow, which is about less than Boston, falls in an average winter. Once every five or six years, a tropical storm, accompanied by very high and potentially damaging winds and heavy rain, will strike the region. About once every 11 or 12 years a hurricane brings damaging winds and storm surges to the region. Several Category 3 storms have struck Cape Cod since record-keeping began, such as a hurricane in 1869, the 1938 New England hurricane, and Hurricane Carol in 1954. Strong Category 2 storms, such as the 1869 Saxby Gale, Hurricane Edna in 1954, and Hurricane Bob in 1991, also caused considerable damage. Notable Category 1 storms include the 1944 Great Atlantic hurricane and Hurricane Donna in 1960. Other notable storms include the Gale of 1815, which would likely have been rated a strong hurricane on the Saffir-Simpson scale, and the so-called "Perfect Storm" of October 31, 1991. The February 2013 nor'easter produced winds in excess of and dropped over of snow on some parts of Cape Cod. The storm knocked out power to tens of thousands of Cape Cod residents, some for up to two weeks. Native population Cape Cod has been the home of the indigenous Wampanoag for centuries prior to European colonization. They lived from the sea and were accomplished farmers. They understood the principles of sustainable forest management, and were known to light controlled fires to keep the underbrush in check.