Don't Panic - Should be not too much to worry about from our point of view. This is the NOAA description of an S3 storm -
Biological: radiation hazard avoidance recommended for astronauts on EVA; passengers and crew in commercial jets at high latitudes may receive low-level radiation exposure (approximately 1 chest x-ray).
Satellite operations: single-event upsets, noise in imaging systems, and slight reduction of efficiency in solar panel are likely.
Other systems: degraded HF radio propagation through the polar regions and navigation position errors likely.
Three things may be interesting -
1. Does it affect the satellites for geocaching? (most important)
2. Does it effect any other radio / tv / internet transmissions
3. Do you see an aurora? (May be possible - the closer to the poles the better the chance)
I would be interested to see your feedback for these for the next 24 hours
For the geeks - this is a result of the 2nd largest solar flare so far of solar cycle 24 and a direct hit geomagnetic storm on earth is fairly rare - ie most miss. Solarham.com is a wealth of information and links if you wish to learn more.
Picture below - Prediction of Solar Winds at about 9:00pm tonight Melbourne Time. The white is about 900km/s (fast) Earth is the green dot. The other two dots are forward and backward stero satelites that take pictures of the sun.
