Does the moon affect the Earth's climate? So, this morning I was talking to a friend about astronomical observations, and he told me that lately there has only been good weather when there was a full moon in the sky, which was a shame. 
I jokingly said: 'maybe there's a correlation!', but then I started thinking: wait, if the moon can affect the oceans, why shouldn't it also make an impact on the atmosphere, which is just another fluid. So... are there atmospheric tides? Does the moon affect the weather or the climate in a significant way?
 A: The moon DOES affect weather but not significantly.
Just like it affects ocean tides, it affects the atmosphere in a similiar way. When the moon is full or new for example, it creates a "bulge" in an ocean, which is why we have tides. A similar thing happens with the atmosphere; it attracts the atmosphere to itself.
When the Sun, moon and Earth line up, and the moon is at its perigee (closest to the Earth), you can expect lower temperatures. This is due to the combined gravitational pull of the moon and the Sun.
Nobody is completely sure how the moon affects weather exactly, but it doesn't affect it significantly.
A: It might affect climate, but not on the time scale of a month, and does not significantly affect the weather.
The fact that the moon exists may significantly stabilise the inclination of the Earth relative to the Sun.  This, in turn, affects climate in the long run.  The debate is ongoing.  For example, see long term axial tilt (Wikipedia):

The Moon has a stabilizing effect on Earth's obliquity. Frequency map analysis suggests that, in the absence of the Moon, the obliquity can change rapidly due to orbital resonances and chaotic behavior of the Solar System, reaching as high as 90° in as little as a few million years. However, more recent numerical simulations suggest that even in the absence of the Moon, Earth's obliquity could be considerably more stable; varying only by about 20-25°. The Moon's stabilizing effect will continue for less than 2 billion years. If the Moon continues to recede from the Earth due to tidal acceleration, resonances may occur which will cause large oscillations of the obliquity.

There are also atmospheric tides, but lunar atmospheric tides are very weak.  To detect a lunar signal in weather patterns can be difficult, because other signals are so much larger, and there is noise too.  So if your friend thinks it's only been good weather during full moons, that's either a coincidence or confirmation bias.
A: There are tides in rocks and those tides affect volcanoes and volcanoes can affect climate.

Scientists have not yet found any correlations between land tides and earthquakes but they have found a relationship between the tides and volcanic eruptions because of the movement of magma or molten rock inside volcanoes (USGS). 1

A: I think the moon and sun do affect the weather more than we are led to believe, the moon is getting farther away and the sun is getting larger, these both must have an impact on earth.  The suns solar flares and mass corona ejections also play a part.
I believe small changes in the moons orbit and distance and the suns swelling has a bigger impact on the weather than anything man can achieve.
Scientists are getting to hung up on the man made climate change Idea and need to broaden there thinking and not be afraid to speak out.
A: If the moon is on the opposite side of the planet while the sun is over our heads, I would be under the impression the moon pulling the atmosphere towards it would allow warmer days or cooler nights as the atmosphere is thinner during this time. 
