The main limitation of this test account is that you can only use it to fetch data from locations in Cape Cod, Massachusetts.
Photo by Henrik Dreisler
The rate limit on the test account is also pretty low. You're particularly likely to hit it if you're making big requests (see the explanation of request units on the pricing and sign-up page for proper API accounts). But the rate limit on the test account will hopefully be enough for basic development and testing purposes.
Useful resources for finding your way around Cape Cod
Our Degree Days.net web tool - search for "Cape Cod" and click "map" to get a map of weather stations. Also try a search for "Truro, MA" to find the stations in the North-East corner of Cape Cod. If a station is on Cape Cod, you can fetch data for it using the test account above.
FindLatitudeAndLongitude.com - click anywhere within Cape Cod on the map to get a longitude/latitude position. You can then request data from that position through the API, and the API will choose the best weather station(s) to use automatically. Note that the API takes longitude/latitude co-ordinates, but FindLatitudeAndLongitude.com lists them as latitude/longitude co-ordinates, so you'll need to swap the two numbers around. Also make sure to get the decimal values (e.g. longitude -70.305634, latitude 41.695475), not the ones expressed in hours, minutes and seconds.
Cape Cod zip codes - you can request data from all Cape Cod zip codes using the test account above, and the API will select the best weather station to use automatically. Note that zip codes are called postal codes by the API (as the API works with codes from a wide range of countries). Note also that, when requesting data from a Cape Cod postal/zip code, you'll need to specify "US" as the country code (Cape Cod being in the US, of course).
We hope you enjoy your trip to the Cod, and please do let us know if you have any problems. There's not much we can do about the weather or the fish, but we can certainly help if you're having trouble with your API integration.