SVT occurs due to re-entry of current into the cardiac muscle
from an abnormal tissue of the heart which is not suppose to produce electrical activity.
As you are controlling it through the use of medications you will have to take these medicines according to the doctors advice and will have to take them regularly.
There are maneuvers which help with the svt. Valsalva maneuver
is one in which you can hold your breathe and try to exhale forcible as if trying to clear your bowels. second is carotid massage
in which you can gently massage your carotid area.
there are ways in which this problem can be treated such as radioablation and cryoablation
. Cryoablation is in which you freeze the tissue of the heart which is producing this tachycardia
. but the temperatures required are much below that of freezing point, i think this is why you were asking if the cold weather helps. I do not think there is any study to show that cold temperature helps.
SVT can also occur due to intake of high caffine use so i suggest you do not use it.
I hope this information was useful.
Take care of yourself