Dyfed-Powys Police have taken to social media to warn drivers of potential disruption on the roads today.
The post is thought to be connected to protests organised by the farming community.
A police spokesperson said: “We are aware of potential disruption to traffic in Carmarthen and Aberystwyth town centres from midday today.
“The traffic network in and out of the towns may also be affected.
“If you are planning on travelling in those areas today, please consider changing your route or journey time to avoid delays.