She claimed the 20km elite time-trial title on the Saturday and placed second in the 100km road race the following day. This comes after her victory in the previous weekend's Bouckaert-Soenen road race.
"The Western Cape champs were one of the major goals that I had set for myself in December to get in to a positive state of mind for the season ahead," said van der Merwe.
"I wanted to be the elite champion, so I worked hard and got my mindset right for both races.
"My training over December was very different. I did a lot more intervals and focused on my weaknesses."
Despite her surge in form, Van der Merwe said there was still room for improvement.
"This year, I would like to improve my racing skills. I need to be able to race smart when it comes to the timing of attacks and sprints."
She will take part in tomorrow's 99er Cycling Challenge in Cape Town before joining her teammates at the SA National Road Championships in Durban.