There is no physical or chemical scenario which would permit
the OP's gas to undergo sustainable combustion at 10 Celsius* but not at 3 Celsius other than the liquid (in the case of butane ) source not being above its boiling point.
The vapour pressure of propane
in normal Texan weather
will always be hugely in excess of the regulators input requirements. If the OP is certain that his LPG is propane
, not butane, then his ignition source should be examined or the reg replaced.
*apolologies for the use of of this unit of temperature on a US-centric forum, perhaps this explains the choice.