The METAR is the determining factor. Here’s an excerpt from the IFATC manual:
Pattern work should only be approved in Visual Metrological Conditions (VMC) as a MINIMUM – this is 3 statute miles (approx. 5000 meters) visibility and a cloud base of 2000ft Above Aerodrome Level (AAL).
You can learn more about how to read the METARs in the #tutorials section here: