SebastianK

This Plugin is very easy to handle. Just install with a few clicks and set it up in your configs. 
Then include it in your sidebar e.g. with the following code:
< ?php spWeatherShow(); ? > (without spaces)

spWeather

This Plugin gets the weather from google.de/google.com and shows the weather now and a 4 days forecast with tiny pics

MorganF

Weather Layer is a plugin which allows you to display a layer with weather information for a choosen city.
For example, if you want to display weather for Paris into a post, you just need to insert the following shortcode :
[weatherlayer country=”France” city=”Paris”]
This will display a horizontal layer with weather information related to Paris, France. This format fits well for single posts. However, if you want to insert a weather layer into your sidebar, the WL widget is what you need. Drag and drop it in the widgets menu then fill the form.
Finally, if you want to display a vertical layer with a shortcode, use this :
[weatherlayer country=”Japan” city=”Osaka” display=”vertical”]
Supported languages are English, French, Spanish, German, Italian, Russian, Japanese and Polish.
NB : 
This plugin is using Open Weather Map.

Weather Layer

do_shortcode

Display weather data on your blog thanks to Open Weather Map. Example of use : [weatherlayer country="France" city="Paris"]

spWeather vs Weather Layer