How to calculate Average of daily data to fill missing values

[mahjid]

Hello all,
I have a time series data of daily precipitation for 25 years. These data have huge number of missing values. I want to reconstruct the missing values by calculating the mean of rainfall for before and after that specific date. For example the rainfall for date 1/1/1990 is missing. I want to calculate the average of all rainfall for dates 1/1/1985, 1/1/1986,…, 1/1/1989, 1/1/1991,…,1/1/2010 except the missing one. My question is how to write an equation in excel to do the operation fast. The attached file is a sample of work to be reconstructed. The red column is the SUM and MEAN of all data I calculated them manually but I need a faster way. Any help highly appreciated.
Thank you in advance.

[XOR LX]

Hi,

The AVERAGEIFS function will give you the mean of a dataset (and ignore non-numerical entries in its calculation), so, for example, in cell J2 of your sheet this formula will give you the average (mean) daily rainfall for 2nd April over the years given:

=AVERAGEIFS($D$2:$D$9497,$B$2:$B$9497,H2,$C$2:$C$9497,I2)

Copying this formula down will give similar results for the corresponding day/month in each row.

Regards

[mahjid]

Thank you very much dear XOR LX. Your help was what I was looking for.

[XOR LX]

You're welcome.