The ground-based World-Wide Lightning Location Network (WWLLN) has continuously monitored global lightning since 2004.  We are pleased to make available monthly thunder hour time series derived from WWLLN lightning detections.  The number of WWLLN stations has been largely consistent since 2013, so thunder hour data are available for 2013-present.  These time series are available for climatological research purposes.

What are thunder hours?

Conceptually, thunder hours represent the number of hours during which you would hear thunder at a particular location.  The distance at which thunder is audible depends on many factors (see summary in DiGangi et al. 2022), but for the purposes of this climatology, we assign a thunder hour to any grid box within 15 km of a WWLLN stroke during that hour.


Monthly thunder hours for the full period of record, illustrating both seasonal and interannual variability.

Thunder hours over the Arctic, outside the field of view of geostationary lightning sensors:  yearly animation and climatological-mean plot for May-September.

Data access

The WWLLN monthly thunder hour dataset is available for research (i.e., non-commercial) use.  Further information about the dataset can be found in the readme.  When using the data, please include the following statement:  “The authors wish to thank the WWLLN (http://www.wwlln.net), a collaboration among over 50 universities and institutions, for providing the lightning data used in this paper.”


Please send questions to Katrina Virts or Bob Holzworth