Geomagnetic solar activity has a significant impact on human well-being (exacerbation of disease, malaise, headache, etc.) as well as some technical devices (GPS satellites etc.).

Data source: http://www.swpc.noaa.gov/
Solar Geomagnetic Activity transcription:

K < 4 - Quiet (Green Sun Icon)
K = 4 - Raised (Yellow Sun Icon)
K > 4 - Storm (Red Sun Icon)

Click on widget to see activity graph image.

Some features:
- Archive data for last 30 days
- Forecast data for 3 days
- Forecast data for 27 days (largest index of the day)
- Storm begin notification
- Sharing image of a solar activity chart

More info: http://www.swpc.noaa.gov/products/planetary-k-index