As a Landscape photographer, you are always interested in best light for shooting at locations. You are constantly chasing the light, you need to know when the golden hour or the blue hour would be. Luckily there are lot of free and paid tools available for you to help you plan your shoot according to your desired location.
Another great factor to have in your images are clouds because at these special times of the day they will produce some amazing colours in the sky. Even outside these hours clouds give the image a greater context rather than a simple blue sky filling the frame. Consider the following images, without clouds and with clouds. Personally, I like the one which has some clouds in the sky otherwise the the blue sky is just an empty void.
The Photographers Ephemeris
This application and app (iOS and Android) lets you plan your shoot and identify exactly based on your vantage point where different elements like the sun and moon will be. It also tells you the sunrise, sunset, moonrise and moonset times. The desktop version is free to use and you can plan everything on your computer. The Smartphone Apps are paid though but its a worthwhile investment if you are a avid shooter.
The weather is also important part of your planning. Are you going to have rain? Is it going to be clear? One of the other things that some of us overlook is the “Cloud Cover”. This will help you identify whether you are going to see any blue stuff or greys or bit of both. Generally, 30-40% cloud coverage is quite good as it lets you get some nice landscapes. Some clouds will give greater impact to your image vs no clouds which may overpower the image with too much blue.