A thin cloud cover over much of central Namibia is a clear signal that the water in the Pacific Ocean, very far away from our shores, is getting colder. The South Pacific weather picture has been showing a definite shift into the La Nina range for the past four months.
This weather pattern is evidenced by a drop in the Sea Surface Temperature (SST) across the eastern equatorial Pacific Ocean. The SST there is now some 4oC below normal.

What happened
The sequence of cold weather and overnight frost came and partially went. A return to warmer days was in place by Tuesday: but persistent wind limited the day-time warmth. The new cut-off low arrived and came into its own over the Karoo during Wednesday.