Loop daily average of hourly data

Hi there, I'm trying to make a loop to get daily average of temperatures from five stations in june. I have a cell of 5x1, each cell for each station, them I make an intersect to get each day of the month, june = 30 days.

for jj= 1 : length(Matrices)%stations(5)
    for ii= 1 : length(M_24h)% days (30)
        Matriz_24h{jj,1}(ii,8:9)=nanmean(Matrices{jj,1}(B1(ii,1):B1(ii+1,1),8:9)); 
end

I run the code, but at the end, it doens't get the average daily of the last day, I know that the time of the last day is until 23 hs, but I don't know how to get it.

result

day : 1, 2, 3, 4, 5, 6, 7, 8, ... 30

Average: 20.5 , 20.7, 21.2, 20.6, 21.8, 20.3, ..... NaN

Thanks