A few years ago, while on a camping trip on the Maine coast with my Dad, I photographed the moon coming up directly behind a lighthouse over a mile offshore. It wasn't the greatest photo, but when showing my Dad, he commented how it was once in a lifetime to get the moonrise lined up so perfectly behind the lighthouse- making me realize how spoiled we are as landscape photographers these days.
Of course, lining that photo up isn't "once in a lifetime" anymore. There are countless resources available now to help plan precise compositions and predict weather, but some are better than others. Over the past few years, I've done a lot of testing, narrowing everything down to a handful of websites and apps that I've found to be accurate. These are resources that help me every time I'm planning a shoot, and I hope they help you too!
In addition to a beautiful user interface, Ventusky offers hourly weather forecasts that I've found to be very accurate. I prefer this cloud cover forecast over others (such as NOAA's), because it shows offshore clouds as well. They've also just added the option to forecast cloud height as well, very helpful!
A great website for planning sunrises, sunsets, and night photography.
DarkSky is a great website and app for weather forecasting, also very accurate. I always check both Ventusky and Darksky to get an idea of the forecast.
When planning any hike in the White Mountains, I always check the Higher Summits Forecast, put out by the Mt. Washington Observatory. The mountains have their own weather, and it's important to check both forecasts- both for your safety, and to get the conditions you want!
Another resource for planning around mountain weather, with localized forecasts for summits all over the world. Aside from the obvious use of planning for hikes, I like to check these forecasts anytime I plan on photographing around the mountains. For example, when photographing the night sky at a lake or pond with a mountain background, I'll check to make sure that mountain's summit will be clear as well. Even with completely clear skies overhead, summit fog can form that rolls off into your scene, obstructing the stars.
ClearDarkSky provides cloud cover forecasts specifically for astronomy, which of course carries over nicely for astrophotography.
Aurora-Service is my favorite resource for monitoring space weather, AKA the Aurora Borealis. This site has all the information you need in one place, including the Aurora Ovation, current KP index and forecast, and realtime data.
An iOS/Android app, this is the best $10 you can spend on photography. There are too many features to list here, but the main draw for me is the Planner function. Using Google Earth overlays, you can see exactly where the Sun, Moon, and Milky Way will be in any location, at any time. I use this app every time I'm out shooting.
Another resource utilizing Google Earth overlays, The Photographer's Ephemeris is both an app and a website. I prefer PhotoPill's interface and functionality a bit more, but TPE has a free desktop version for planning around sun and moon rise/set.
The heart of all planning, Google Earth Pro for desktop. While the app does work well, the desktop version has much more functionality, providing many useful features for photographers. With beautiful satellite images that provide an impressive amount of detail while zoomed in, Google Earth makes it easy to scout new locations before visiting.
This website is useful for planning astrophotography trips, with a map overlay giving light pollution levels. This is just meant to give a general idea of how bad the light pollution is in a given area, but that doesn't mean every random streetlight or house is accounted for. In combination with Google Earth, you can generally get a good idea of what the level of light pollution will be.