Apparatus for transcutaneous electrical nerve stimulation in a user, the apparatus comprising: a stimulator (105) for electrically stimulating at least one nerve with at least one stimulation pulse； a controller (520) connected to the stimulator for controlling at least one characteristic of the at least one stimulation pulse； an analyzer (540) for identifying the current and future presence of pain- altering patterns based on weather and/or environmental factors； and a processor (535) connected to the analyzer and the controller for modulating the at least one characteristic of the at least one stimulation pulse according to the pain-altering patterns identified by the analyzer.
