California - any time of the year.
California is long - over 1,000 miles, which is more or less double* the length of Britain (*depending which criteria you use) therefore the temperatures between the northern and southern-most areas varies greatly, enabling visitors to enjoy a pleasant climate at any time of the year, somewhere in the 'The Golden State'. There are also differences between coastal regions and inland (mountains, valleys and deserts). At the time of writing, mid-October, the current temperatures midnight-midday are: North Lake Tahoe 34F - 66F (1C - 19C) San Francisco 49F - 63F (9C - 17C) Sacramento 55F - 81F (13C - 27C) South Santa Barbara 52F - 67F (11C - 19C) Los Angeles 62F - 66F (17C - 19C) Palm Springs 69F - 91F (21C - 33C) One reason why wealthy people often have homes in Palm Springs is quite obvious; there is also the aerial tramway and many golf courses. By contrast, Lake Tahoe is close to Mammoth and June mountains...