and land speculator David Jacks. The closed-cone pine habitat is dominated by Monterey pine, Knobcone pine and Bishop pine, and contains the rare Monterey manzanita. In the early 20th century the botanist Willis Linn Jepson characterized Monterey Peninsula's forests as the "most important silva ever", and encouraged Samuel F.B. Morse (a century younger than the inventor Samuel F. B. Morse) of the Del Monte Properties Company to explore the possibilities of preserving the unique forest communities. The dune area is no less important, as it hosts endangered species such as the vascular plants Seaside birds beak, Hickman's potentilla and Eastwood's Ericameria. Rare plants also inhabit the chaparral: Hickman's onion, Yadon's piperia (Piperia yadonii) and Sandmat manzanita. Other rare plants in Monterey include Hutchinson's delphinium, Tidestrom lupine, Gardner's yampah and Knotweed, the latter perhaps already extinct. Monterey's noise pollution has been mapped to define the principal sources of noise and to ascertain the areas of the population exposed to significant levels. Principal sources are the Monterey Regional Airport, State Route 1 and major arterial streets such as Munras Avenue, Fremont Street, Del Monte Boulevard, and Camino Aguajito. While most of Monterey is a quiet residential city, a moderate number of people in the northern part of the city are exposed to aircraft noise at levels in excess of 60 dB on the Community Noise Equivalent Level (CNEL) scale. The most intense source is State Route 1: all residents exposed to levels greater than 65 CNEL—about 1,600 people—live near State Route 1 or one of the principal arterial streets. Climate The climate of Monterey is regulated by its proximity to the Pacific Ocean resulting in a cool-summer Mediterranean climate (Köppen climate classification: Csb) and closely resembles that of an oceanic climate. The average high temperatures in the city range from in December to in September. Average annual precipitation is , with most rainfall occurring between October and April, with little to no precipitation falling during the summer months. There is an average of 72.1 days with measurable precipitation annually. Summers in Monterey are often cool and foggy. The cold surface waters cause even summer nights to be unusually cool for the latitude, opposite to on the U.S. east coast where coastal summer days and nights are much warmer. The extreme moderation is further underlined by the fact that Monterey is on a similar latitude in California as Death Valley – one of