you’d need to connect the 1-wire temp probe to the appropriate Raspberry Pi GPIO pin, install the driver, and modify the sprinkler app to read and use this as current/local temperature, presumably combined with the wunderground data. not sure what you had in mind.
there are lots of how-to’s out there, see for example http://www.raspberrypi-spy.co.uk/2013/03/raspberry-pi-1-wire-digital-thermometer-sensor/
Don