This upcoming weekend looks like great weather in most of the US. This is a great excuse to join for the 2015 spring #mapathon. The theme is the Great Outdoors. Here are the participating communities. Find all details on how to attend on the wiki. Your city's not on the list? It's not too late, get yourself onto the wiki.
For the idea behind #mapathons and tips on how to run one - read up on "This Is Why We're Doing #mapathons".