Knowing the prevailing wind direction is essential for planning you route. Constantly battling headwinds is no fun. Temperature and rainfall information are essential for good gear and clothing decisions. When on the road we find yr.no (Norwegian Meteorological Institute) is best at forecasting winds.
Make every possible effort to avoid the rainy season in tropical or subtropical areas.
For average temperatures and rainfall charts and for detailed information on wind patterns, go to Weather Underground.
The History & Almanac section of this page ( at the lower left) allows you to research wind, rainfall, and temperature patterns for places on your ride.
You can see typical wind strength and direction throughout a 24 hour period, and this daily pattern information can be used to see if an early start will help avoid headwinds.