[tex] p [/tex] - it is cold
[tex] q [/tex] - I wear a jacket
[tex] p\Rightarrow q=1 [/tex]
therefore, the following are possible values of [tex] p [/tex] and [tex] q [/tex]
[tex] p=0 \wedge q=0\\p=0 \wedge q=1\\p=1 \wedge q=1 [/tex]
Now, if [tex] q\Rightarrow p [/tex] then we have
[tex] 0\Rightarrow 0=1\\1\Rightarrow 0=0 [/tex]
The second statement is false, so the statement from the question is NOT always true.