For my job I want to find out the temperatures for certain periods of the year.

For example, I hired out a whole lot of wetsuits this month, I want to find out if this was due to warmer weekend temps compared to the same time last year and so on.

Can anyone point me to a website?

S.

www.wunderground.com gives you historical daily/ monthly etc information

Legend. thanks Rach.

http://www.niwa.co.nz/services/clidb
You could try this, its free to sign up.