It's fixing to rain here tonight, in Central California on June 7th to 8th. Maybe this is the explanation.

The sun is at it's lowest sunspot and solar cycle in about 100 years.  Brr!

Figure 1: F10.7 Flux 2014 – 2017

The F10.7 flux shows that over the last three and a half years the Sun has gone from solar maximum through a bounded decline to the current stage of the trail to minimum. Solar minimum is likely to be still three years away.