The south coast counties of Dorset, Hampshire, West Sussex, East Sussex and Kent enjoy more sunshine than anywhere else in the United Kingdom, receiving 1541-1885 hours. Average annual rainfall varies across the county southern and eastern coastal areas receive as little as 741 mm (29.2 in) per year, while the Dorset Downs receive between 1,061 and 1,290 mm (41.7-50.8 in) per year; less than Devon and Cornwall to the west but more than counties to the east.

Dorset has a population of 407,217, plus 165,370 in Bournemouth and 137,562 in Poole (total 710,149 mid-year estimates for 2006). The following statistics exclude Poole and Bournemouth, which are no longer part of the administrative county. 98.7% of Dorset's population are of white ethnicity, an extreme example of the disproportionately small ethnic minority population in rural areas. 78% of the population are Christian and 13.7% are not religious. Dorset has the highest proportion of elderly people of any county in the United Kingdom: 27.4% of the population are over 65.

The county has one of the lowest birth rates of the 34 shire English counties, at 8.7 births per 1000, compared to the England and Wales average of 12.1/1000. It has the third highest mortality rate (12.0/1000), behind East Sussex and Devon. In 1996 deaths exceeded births by 1,056, giving a natural population decline of 2.7 per 1000, however, in 1997 there were 7,200 migrants moving to Dorset and the Poole-Bournemouth conurbation, giving Dorset the second highest net population growth, behind Cambridgeshire, at 17.3.

Dorset County Council is based at County Hall in Dorchester. Following the local council elections in May 2005, 24 Conservative, 16 Liberal Democrat, four Labour and one independent councillor sit on the county council. All Labour councillors were elected in the built up area of Weymouth and Portland; rural areas elected Conservatives and Liberal Democrat councillors.

This pattern is repeated at the national level. South Dorset is represented in Parliament by Labour MP Jim Knight, though this constituency was Labour's smallest majority and was one of the most fiercely contested seats in the General Election of 2005. In the event, the seat went against the national trend and Mr Knight's majority increased slightly on a swing from the Conservatives. In all other Dorset constituencies, the Conservatives and Liberal Democrats are the most successful parties: Mid-Dorset and North Poole is represented by the Liberal Democrats, and West Dorset, Christchurch and North Dorset by the Conservatives.

The built up area of Poole and Bournemouth is divided into three constituencies, Bournemouth East, Bournemouth West and Poole, all of which are represented by Conservative MPs. Dorset, the rest of the south west, and Gibraltar are in the South West England constituency of the European Parliament.