hoursPerDay = 24;
coeff24hMA = ones(1, hoursPerDay)/hoursPerDay;

avg24hTempC = filter(coeff24hMA, 1, tempC);
plot(days,[tempC avg24hTempC])
legend('Hourly Temp','24 Hour Average (delayed)','location','best')
ylabel('Temp (\circC)')
xlabel('Time elapsed from Jan 1, 2011 (days)')
title('Logan Airport Dry Bulb Temperature (source: NOAA)')