Why does cubic interpolation give values that are outside the data range?

I basically want to plot temperature against latitude and longitude.I have heard that cubic interpolation gives negative values and since temperature cannot be negative i wanted to know which interpolation to use?

Answer 1

[Jan]

Linear interpolation does not create values outside the range given by the measurement.

[Charles David]

But what is the difference between these methods.Which algorithms do they use and is linear really suited for my problem?

Answer 2

[Sean de Wolski]

http://mrkwr.wordpress.com/2006/11/08/mark-twain-on-the-perils-of-extrapolation/