Given a graph G $G$, the k $k$‐mixing problem asks: Starting with a k $k$‐colouring of G $G$, can one obtain all k $k$‐colourings of G $G$ by changing the colour of only one vertex at a time, while at each step maintaining a k $k$‐colouring? More generally, for a graph H $H$, the H $H$‐mixing problem asks: Can one obtain all homomorphisms G
→
H $G\to H$, starting from one homomorphism f $f$, by changing the image of only one vertex at a time, while at each step maintaining a homomorphism G
→
H $G\to H$? This paper focuses on a generalization of k $k$‐colourings, namely, (p
,
q
) $(p,q)$‐circular colourings. We show that when 2
<
p
q
<
4 $2\lt \frac{p}{q}\lt 4$, a graph G $G$ is (p
,
q
) $(p,q)$‐mixing if and only if for any (p
,
q
) $(p,q)$‐colouring f $f$ of G $G$, and any cycle C $C$ of G $G$, the wind of the cycle under the colouring equals a particular value (which intuitively corresponds to having no wind). As a consequence we show that (p
,
q
) $(p,q)$‐mixing is closed under a restricted homomorphism called a fold. Using this, we deduce that (2
k
+
1
,
k
) $(2k+1,k)$‐mixing is co‐NP‐complete for all k
∈
double-struckN $k\in {\mathbb{N}}$, and by similar ideas we show that if the circular chromatic number of a connected graph G $G$ is 2
k
+
1
k $\frac{2k+1}{k}$, then G $G$ folds to C2
k
+
1 ${C}_{2k+1}$. We use the characterization to settle a conjecture of Brewster and Noel, specifically that the circular mixing number of bipartite graphs is 2. Lastly, we give a polynomial time algorithm for (p
,
q
) $(p,q)$‐mixing in planar graphs when 3
≤
p
q
<
4 $3\le \frac{p}{q}\lt 4$.