Links to live weather stations so that you can check the weather before you go for your trail run 
Jonkershoek
http://lognet.saeon.ac.za:8088/Dwarsberg/index.html
Drakensberg (Cathedral peak)
http://lognet.saeon.ac.za:8088/mikes_pass/index.html
Constantiaberg (Table Mountain Nature Reserve)
http://lognet.saeon.ac.za:8088/Constantiaberg/index.html
Have fun. Stay safe.