It depends.
The first thing to keep in mind is that although there are certainly some things that can influence the transformation into a werewolf, these things do not necessarily universally cause involuntary transformations (under normal conditions).
Halloween is an excellent example.
Halloween and lycanthropy are closely intertwined for a number of reasons. It should therefore come as no surprise that were you to ask 100 random people what night would they be most likely to spot a werewolf, the top two answers would be either 1) during Halloween or 2) during a full moon…and why is this? It is not because Halloween causes werewolf transformations and all werewolves are therefore predestined to transform on October 31…no, rather it is because Halloween (for a number of historical reasons) has a strong pull and influence over transformations….very like the pull and influence a full moon has over a werewolf.
What this means is that younger or newer werewolves may find that the “pull” or “urge” to transform is practically irresistible…to them it may be almost impossible not to transform! And so, the answer for them would be yes, they will without doubt transform this Halloween.
This is not however the case for everyone.
Older werewolves, or those that have been werewolves for a longer period of time, naturally start to gain a little more control over when they transform and therefore may not necessarily undergo an involuntary transformation on Halloween. This is not to say that they won’t feel the same urge to transform.
It is also important to keep in mind that external forces can trigger werewolf transformations…things like stress, hunger, and excitement…combined with a day like Halloween..can cause even older experienced werewolves to have involuntary transformations! In addition, if Halloween were to fall on the same day as a full moon it might be virtually impossible for any werewolf (old or young, experienced or new) to prevent a transformation! (Side note: this year Halloween does not fall on a full moon…to be precise it falls almost exactly halfway between full moons!)
So what does all this mean?
In short: if you want to transform, Halloween is just as good as a full moon for it happening. If you’re new or a young werewolf, be prepared to transform – possibly and probably involuntarily. If you don’t want to transform, you might have to work at it, especially if you’re a newer werewolf…keeping stress, excitement, and your mind calm can help you control it!