Data of daily observations at all meteorological stations in the European part of Russia for 1981-1990 have been used to establish the correlations between daily and ten-day mean values of air pressure and precipitation amount. Also, we estimated analogous correlations between precipitation amount and air temperature. The correlation coefficients for the ten-day mean are significantly (up to 1.5-2 times) higher (in the absolute value) than those for the daily mean.