Joseph:

I don't know what types of weather records might be available for Mexico, especially for the year you specified - 1793. However, it seems to me that military reports for that time period would include weather reports. I don't know where such military reports would be archived, but my guess would be that they are in the national archive of Mexico in DF or in Spain.

I googled < weather records mexico > and one of the sites I came across was for the "Instituto de Geografia, UNAM". Try these sites - they don't have what you asked about, but there is some other cool information:

http://indy2.igeograf.unam.mx/instituto/index.html

http://indy2.igeograf.unam.mx/instituto/publicaciones/atlas_nacional.htm

http://indy2.igeograf.unam.mx/instituto/publicaciones/atlas_con.html#Hi…

(I didn't check the Links section of Nuestros Ranchos to see if they are already posted.)

Have a good weekend.

Natalie in VA