For those times when weather dictates whether a trip is feasible.
Produce historical weather averages for a given series of locations and dates. Less abstractly, for a given route e.g. thru-hike, cycling tour, with start and end dates, return a day-by-day historical average of the weather at each location.
- forecast.io
- wunderground
- yahoo weather
- NCDC three decade climate normals
- weathersource looks to have exactly what we need - 10 year averages by lat/lng, but it's $2,250/month!