The United Nations Food And Agriculture Organization (FAO), AgroMet division, has compiled a database of climatic information gathered between 1961 and 1990 from close to 30,000 observation stations. This database, and applications designed to extract, analyze and map the data, are available online.
The full database with analysis programs is available here (warning: it’s a 150 MB download). Read the enclosed DOC file for the installation instructions for the data and the two helper programs. The first program, FAOCLIM2, is mainly intended for use in exporting data from the database in either table or CSQS (comma-separated value) formats (click on the image for an enlarged view):
You can select observation stations individually, by country, or using an interactive map. Average climatic data over the entire period can be chosen, or data from a set of years can be extracted to construct a time series. Here’s a plot of mean annual precipitation for Peru in Google Earth, using data exported from FAOCLIM2:
The other program included in the FAOCLIM package, GeoContext, lets you query and chart data from individual and multiple observation stations using a geographical interface:
If you don’t need all the FAOClim data for every year from 1961-1990, but are more interested in just the average data, you would be better off with Juergen Grieser’s LocClim application. It’s not only smaller at about 17 MB, but also interpolates data for locations between observation stations, including altitude effects, so that you can get approximate average climatic data for most points on the earth:
You can also create month-by-month plots of different climatic parameters for the location you’re interested in, and export data in a variety of formats. There’s also a web-based version of LocClim that will return mean climatic data for any geographic location you enter.