Use Google Maps to pinpoint the location you are interested in and the app will calculate up to date magnetic variation (declination), dip angle, total field and other magnetic field components using the latest World Magnetic Model (WMM2015).
The model developed and distributed by NOAA accurately predicts the main magnetic field anywhere on the globe as it changes daily and is valid until 2020.
If you need to do any kind of navigational planning you will need to know about the Magnetic Declination to properly calculate the Compass Heading. This app will do that - a lot more, if you are interested in the Global Magnetic Field.
Keywords: Magnetic Variation, World Magnetic Model, Geomagnetism, Navigation, Magnetic, Magnetism, Compass Heading, PPL, Flight Planning, NOAA.