growing season in the United Kingdom is defined as starting on the day after five consecutive days with mean temperatures above . The season finishes the day after mean temperatures are below for five consecutive days. Areas in Hardiness zone 9 experience an average lowest recorded temperature each year between . Figures are for Weymouth and Portland as a whole. These figures are for July to September in 2010. Citations Further reading Anon 1905, The Portland Year Book and Island Record 1905, reprinted 2004, Portland Museum, Portland, Dorset, 68 pages Theresa Murphy, Murder in Dorset 1988. Robert Hale Limited, London – Portland chapters Stuart Morris, 2016 Portland, an Illustrated History The Dovecote Press, Wimborne, Dorset: Geoffrey Carter, 1999 Royal Navy at Portland Since 1845. Maritime Books, . Stuart Morris, 1998 Portland (Discover Dorset Series) The Dovecote Press, Wimborne, Dorset: . Rodney Legg, 1999 Portland Encyclopedia. Dorset Publishing Company, . Jackson, Brian L. 1999. Isle of Portland railways. Palmer, Susann. 1999. Ancient Portland: Archaeology of the Isle. Portland: S. Palmer. Stuart Morris, 2002 Portland: A Portrait in Colour The Dovecote Press, Wimborne, Dorset: . Stuart Morris, 2006 Portland, Then and Now The Dovecote Press, Wimborne, Dorset: . Dorset: The Royal Navy Stuart Morris, 2011, The Dovecote Press, Wimborne, Dorset: . Features Portland. Weymouth & Portland, Stuart Morris 2012. The Dovecote Press, Wimborne, Dorset: . External links Map sources for grid reference . Portland's Tourism Website Portland Town Council Last Ferry Crossing Headlands of Dorset Islands of Dorset Liberties of Dorset Tourist attractions in Dorset Peninsulas of England Populated coastal places in Dorset Jurassic Coast Sites of Special Scientific Interest in Dorset Tied islands Tombolos Natural regions of England Natural regions of Dorset Weymouth and Portland