GPS

[lw395]

The rain might nobble the iphone gps, as a wet windscreen could be quite lossy.
The inbuilt system ought to be more resilient, but it could have been operating with a poor margin for the last year, you wouldn't know until the rain tips it over the edge.

 

[jwilson]

Thick wet cloud, wet windscreen possibly with heater elements in, all reduce signal strength. If it usually works though most likely someone jamming in a vehicle on the same route.

 

[RobF]

I've found the iPhone GPS sensors to be more sensitive than any other device I've used - including a variety of Garmin kit. iPhones work indoors reliably, although they are probably helped with a 'helper' fix from the nearest mast.

I would concur with the others - that there were probably a few jammers in the region - although it could have been a test to stop GPS guided missiles getting anywhere close to a sensitive facility about 20 miles away.