Researching another question, I came across a quote I was looking for that seems to show werewolves only transform in the moonlight:

A cloud shifted. There were suddenly dim shadows on the ground. Their party was bathed in moonlight.

Snape collided with Lupin, Pettigrew, and Ron, who had stopped abruptly. Black froze. He flung out one arm to make Harry and Hermione stop.

Harry could see Lupin's silhouette. He had gone rigid. Then his limbs began to shake.

"Oh, my --" Hermione gasped. "He didn't take his potion tonight! He's not safe!"

I had always figured that when he was in the Shrieking Shack he was shaded from the moon, so it didn't affect him. But then I thought about his school days - where was he when he transformed? The Shrieking Shack! And if it does take moonlight, why couldn't he just hang out in the dungeons or somewhere else in Hogwarts?

Anyone see a way to reconcile these?

  • 4
    Wayyy behind on this one, but only just saw the question - I always assumed the point of the Shrieking Shack was not to hide him from the moon, but to give him a safe space to be wolfy. The Shrieking Shack is rumoured to be haunted because of villagers hearing Lupin's howling - as a wolf. So, he does transform in the Shack, regardless of direct moonlight. They didn't want to leave him in the castle as other pupils would hear and panic. The moon coming out at that point is just dramatic effect, and reminds the characters of Lupin's condition.
    – Luna
    Commented May 6, 2015 at 10:50
  • 1
    @Luna I agree—but by the time he transforms in PoA, the Moon is already high enough to be behind clouds and casting dim shadows on the ground. That means it must have been a full moon for quite some time (even before sunset). David’s answer below gives an explanation that just about almost kind of makes sense, but it seems an odd stretch. Really, Lupin ought to have transformed several hours before he did here. Commented Feb 17, 2016 at 0:55
  • @JanusBahsJacquet A full moon rises exactly at the moment of sunset. The full moon occurs only on the night when the moon is exactly on the opposite of the Earth from the Sun. So when the Sun sets, the full moon rises, and when a full moon sets, the sun rises. On other nights, moonrise does not coincide with sunset. The moonlight scene in the movie implies the moon had risen much sooner, but was obscured by distant clouds and hills. The implication was that Lupin must be in moonlight. Maybe the Shrieking Shack had windows or cracks in the boards that allowed Lupin to see moonlight.
    – RichS
    Commented Jul 9, 2017 at 5:21
  • I don't have a full answer so this is just a comment, but didn't he have to take a potion everyday (even for a few days before)? I could be wrong but if he only missed the current days dose it might mean that only direct moonlight was strong enough to start the transformation (like he was partially vaccinated but missed a top-up), and that if he hadn't taken ANY of the doses he would transform the moment the moon came up as normal - that could explain the need for moonlight on this occasion instead of just the moon being up
    – Matt
    Commented Jul 14, 2018 at 15:57
  • Good idea, but the potion doesn't stop him transforming, it only stops him going berserk when he does.
    – A. B.
    Commented Mar 24, 2021 at 10:06

3 Answers 3


This may be a stretch, and it's certainly not canon (but it is loosely based on canon). I wouldn't even put it as an answer except that your final question asked "Anyone see a way to reconcile these?"

This is a way to reconcile these...

Before that night's events started, Hagrid sent the following note to Harry:

Lost appeal. They're going to execute at sunset. Nothing you can do. Don't come down. I don't want you to see it. Hagrid.

Given the timing of the scheduled execution (sunset), it wouldn't be dark immediately at the time of the execution. It usually takes a half hour or so after sunset for it to become full dark. That gives just enough time for the events to unfold in-between the scheduled execution time and Lupin's transformation.

That means that it's possible that Lupin's transformation wasn't directly caused by the moonlight, but by the onset of full dark. The moon coming out from behind the clouds at that time was coincidence (and a good coincidence for dramatic effect).

  • "That means that it's possible that Lupin's transformation wasn't directly caused by the moonlight, but by the onset of full dark." Ah, but it is not a coincidence that the full moon rises exactly at the onset of darkness. The full moon occurs only on the night when the moon is exactly on the opposite of the Earth from the Sun. So when the Sun sets, the full moon rises, and when a full moon sets, the sun rises. Waxing and waning moons rise and set at moments other than sunset and sunrise.
    – RichS
    Commented Jul 9, 2017 at 5:16
  • @RichS - The moon is quite often visible in the daylight. Full moons included. Not sure where you're coming from with that. bing.com/images/search?q=full+moon+in+daytime&FORM=HDRSC2 Commented Jul 9, 2017 at 16:56
  • I know the moon is often visible in daylight. I often see it in daylight. o_O Full moons are only visible from sunset to sunrise. I checked the image search you provided. Many of those are not full moons. Some are close. A moon that is 1 day before or after the full moon can look full to an unaided eye and be visible just before sunset or just after sunrise, but it is not truly a full moon. Werewolves are affected by the light of a full moon, not the moonlight from a day-before-full-moon. :-)
    – RichS
    Commented Jul 9, 2017 at 22:56
  • For anyone who thinks this is too pedantic: like me, J K Rowling is fond of astrology herself, so would indeed probably have been familiar with all this about when a full moon rises.
    – A. B.
    Commented Mar 24, 2021 at 9:53
  • I don't think that invalidates David Stratton's answer, if it was supposed to. If the moon rose above the horizon at the moment the sun fell below it, and it wasn't fully dark until half an hour later, the moon would have risen further in that half an hour - high enough to be already clearly visible as described.
    – A. B.
    Commented Mar 24, 2021 at 10:01

I think you're coming from a flawed starting position in werewolves requiring sight of the moon to transform. As you mention, Lupin transformed in the Shrieking Shack without sight of the moon. In this case Lupin's transformation just happened to kick in at the same time as the cloud revealing the moon, for dramatic effect. This becomes more apparent given Hermione's exclamation, as the potion doesn't stop the transformation, it only mitigates the results (allowing the person to remain cogniscent and not give over to the wolf completely).

  • It was not 'sight of the moon', but rather 'moon's sight'. Similar to how parts of the human body exposed to radioactive material mutate, but unexposed parts don't.
    – cst1992
    Commented Feb 23, 2016 at 12:47

A late answer, but there's another possibility.

One thing that RichS touches upon in the comments is that the day before a full moon, as well as the day after, the moon appears full but it isn't. We can, in fact, expand upon this into a potential explanation: If we were to get truly pedantic, a truly full moon only lasts an instant - when the sun is exactly opposite from the moon. Who says that the point of moonrise is close enough to the full moon to trigger the transformation?

The scenario might play out like this, for example (round numbers for the sake of simplicity): In general, werewolves are in their werewolf form at the full moon moment, +/- 4 hours, giving a transformation duration of 8 hours (not too unreasonable). At the particular night in question, the "full moon moment" happens to occur exactly at 2AM. During the events in the Shrieking Shack, it gets dark and the moon rises behind the clouds. Then, they stand outside on the Hogwarts school grounds when, exactly at 10PM, the clouds reveal the full moon.

This is not canon, but I don't think a canon answer can be given to this one. Besides, it fits with the slightly pedantic nature of some other spells and magical phenomena.

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