How to take seasonal average of monthly values?

Hello, I have 10 years (120 months) temperature data set. Now I want to take seasonal average of these monthly dataset. season 1 (Jan, Feb, Mar), season 2 (apr, may, june), season 3 (july, aug, sep) and season 4(oct, nov, dec) for every year. Final time series will represent 30 values. Can anyone help me to solve this problem?

[Andrei Bobrov]

Please, small example your temperature data.

[SONI SONI]

Temperature in celsius for a year

Jan 13.34, Feb 16.23, Mar 20.07, Apr 27.02, May 29.07, June 27.36, July 26.17, Aug 25.84, sep 25.55, oct 23.04, Nov 18.74, dec 14.71

Simillarly I have 10 year monthly temperature data.

Answer 1

[dpb]

Depends on storage order...if 10x12 (years x months), then

 Tseas=mean(reshape(T.',3,[]));

If it's already in column order by year, ditch the transpose .'