How can I calculate ensemble average of 6 2D matrices with nanmean function?

Dear All,

I have 6 2D matrices. Both of them have 10958 rows and 30471 columns. The rows are the time and the columns are the space. I would like to calculate the ensemble time average of these martices using with nanmean function. I tried the following way:

pr_h1=repmat(NaN, 10958);
pr_h=repmat(NaN,size(pr_loci_MPI_ESM_LR_CLM));
>> for j=1:10958
for  i=1:30471
pr_h1(j)=[pr_loci_MPI_ESM_LR_CLM(j,i), pr_loci_CM5A(j,i), pr_loci_CNRM_ALADIN(j,i), pr_CNRM_CCLM(j,i), pr_loci_CNRM_CM5_RCA4(j,i), prM_loci_EC_EARTH_RACMO(j,i)];
pr_h(j,:)=nanmean(pr_h1(j));
end
end

but I got the error:

In an assignment  A(:) = B, the number of elements in A and B must be the same.

I would appreciate if someone helped me!