What is Hurricane's accuracy in rain?
With no weather active, Hurricane has an accuracy of 70%. In the rain, however, the accuracy of the attack is boosted. Serebii states that its accuracy becomes 100%.
This move has different accuracies depending upon the weather. In Rain, it has an accuracy of 100%. – Serebii.net AttackDex
Veekun and Psypoke both confirm this as well.
During Rain Dance, this move has 100% accuracy. – Veekun
During Rain Dance, it becomes 100% accurate. – Psypoke
However, Bulbapedia states that Hurricane "cannot miss" in the rain (emphasis mine).
Hurricane cannot miss when used during heavy rain, but has an accuracy of 50% during intense sunlight. – Bulbapedia
This is slightly unclear. It could be trying to state that Hurricane has a 100% accuracy and therefore cannot miss unless the attacker's accuracy or defender's evasion have been modified. It could also be trying to say Hurricane is unable to miss in the rain, similar to Aerial Ace and other similar moves. Does Hurricane have 100% accuracy in the rain, or can it not miss?
It's looking a bit difficult to get a straight answer here, even when comparing to the similar-mechanic moves Blizzard and Thunder.
Bulbapedia says that those three moves cannot miss when used in the correct weather, while Psypoke agrees for Blizzard and Thunder - though it says Hurricane has just 100% accuracy. Serebii gives 100% accuracy to Hurricane and Thunder and ignores Blizzard's weather-based accuracy outright, while Veekun gives 100% accuracy to all three moves.
The interesting bit is Smogon. Its moveslist gives the three moves 100% accuracy in the correct weather. However, there are two catches:
- In its Gen IV sections, it gives the weather-enhanced accuracy of Blizzard and Thunder as "cannot miss".
- From http://www.smogon.com/forums/showthread.php?t=79340:
Hurricane has its accuracy boosted to 100% in rain and reduced to 50% in Sun; its accuracy remains 70% in all other weather. Its accuracy in rain is Swift=like, bypassing accuracy drops and evasion boosts.
One of the posts in that topic explains: "My Vaporeon with Wind Storm [Japanese version of Hurricane] didn't miss after 16 tries with a -6 Stage Accuracy during Rain."
At -6 accuracy, a 100% move is running at 33%, so the odds of hitting 16/16 times are 1 in 43,046,721. So, taking that research thread at face value - and they've the people that decoded the damage formula if I'm not mistaken - then I have to conclude that, like Blizzard in hail and Thunder in rain, Hurricane has infinite accuracy in rain.
Footnote: I remember seeing somewhere during this research that Gen V represents cannot-miss moves with an accuracy of "101%". If you're using an extraction tool that assumes 100% is the maximum (which I would guess some of these sites do), you might get an invalid answer.