Environmental monitoring is extremely important to ensure a safe and wealthy life of both humans and artifacts. Monitoring requirements are extremely different depending on the environment, leading to ad hoc implementations that lack flexibility. This paper describes an implementation that can be adapted to many different applications and embeds the flexibi- lity required to be deployed and upgraded without the necessity of arranging complex infrastructures. The solution is based on small autonomous wireless sensor nodes, small wireless receivers connected to the Internet, and a cloud architecture which provides data storage and delivery to remote clients. The solution permits supervisors on-site not only to have an immediate idea of the current situation by using their smart-phones but also to monitor remote sites through the Internet. All measurements are redundantly stored at different concentration levels to guarantee a safe back-trace and to provide quality assurance also in case of network failure or unavailability. The sensing nodes have small impact, with dimensions which can be of less than 2.5 cm x 1.5 cm when the nodes have to acquire only temperature and relative humidity, and a low cost that enables using them in a set-and-forget way for intervals in excess of one year.