There are still the weather stations, especially in some midwest areas, to inventory. While you are doing that, you might also look into Project BudBurst, operated by the University Corporation for Atmospheric Research (UCAR) – see climate science weblog. This is looking for volunteers to observe when plants bud out or do other climate specific things. The idea is to obtain a database of plant behavior that can be used to monitor climate change.
Project BudBurst (http://www.budburst.org) builds on a pilot program carried out last spring, when a thousand participants recorded the timing of the leafing and flowering of hundreds of plant species in 26 states.The Chicago Botanic Garden, University of Montana, and the USA National Phenology Network (USA-NPN) are collaborators on Project BudBurst, which was funded in part with a grant from the U.S. Bureau of Land Management and the National Fish and Wildlife Foundation. The project is also supported by the National Science Foundation and Windows to the Universe ( http://www.windows.ucar.edu/), a UCAR-based Web site that will host the project online as part of its citizen science efforts.
Project Budburst is one of the citizen-science partnerships of the newly created USA-NPN (www.usanpn.org), which is managed by the U.S. Geological Survey, and includes partners such as the National Science Foundation, the University of Arizona, the U.S. Fish and Wildlife Service and many other agencies. The goal of the USA-NPN is to engage governmental agencies, environmental networks and field stations, educational institutions, and mass participation by citizen scientists in collecting phenological information on plants and animals.
This one needs you to stay put for a period of time so you can be there when a plant decided to do its thing. It would be one way to put a bit of a focus on your appreciation of nature in a different way and gain more from your freedom to be out and about in your RV.