I haven't tested yet, but in Brazil I've found the Airforce Command Moteorology Network's API (https://www.redemet.aer.mil.br/?i=facilidades&p=api-redemet).

Also, the National Spacial Research Institute (INPE) has information about a FTP server in what they called PCD (Data Collection Platform). Information can be found here: http://sinda.crn2.inpe.br/PCD/SITE/novo/site/index.php or webmaster@inpe.br

We also have the National Meteorology Institute (INMET - http://www.inmet.gov.br/portal/) and the Weather Prevision Center and Climate Studies (CPTEC - http://tempo.cptec.inpe.br/).

Hope it helps.