Top 16 weather resources in Spain
1. www.inm.es
This is the official site from the National institute of Meteorology, part of the Ministry of the Environment (Ministerio de Medio Ambiente). The site is all in Spanish, but has excellent and comprehensive weather information with a daily weather map and 7-day forecast for 8,000 towns throughout Spain.
Although it is a little complicated to follow, given that the whole site is in Spanish, it is worth perservering. For example, you can find very specific weather forecasts for each beach in Spain! Search using an interactive map to select specific beaches and get a 2 day forecast, as well as tidal information (for non-mediterranean beaches).
The site also shows a Maritime Forecast, forecast for UV levels throughout Spain and mapped rainfall forecasts over 3 days.
2. www.iberianature.com/material/spainclimates.html
This site is an interesting guide to the natural history of Spain and is an excellent resource for information 
about Spain's environment, geography, climate, wildlife and landscape.
The site gives a climatic overview of the country, dividing Spain into four zones and it provides detailed climate information on four different regions of Spain.
It also has some interesting facts, figures and trivia about Spain, as well as useful articles relating to Spain's weather and geography. These include the EEA report (European Environment Agency) which states that Spain and Portugal will be the two countries within the EU that are most affected by coming climate change.
3. www.bbc.co.uk/weather/world/country_guides/results.shtml?tt=TT008060
The BBC Weather site has an easy-to-read overview of Spain's climate and geography, as well as regional descriptions which also link into charts showing data of monthly average temperatures and rainfall for specific towns.
Nice touches include a measure of "Discomfort from heat and humidity" in each main town and number of "wet" days per months. You can compare relative humidity in Madrid to that of Seville in the south, Coruna in the north east or Las Palmas in the Canary Islands.
4. www.kyero.com
Kyero.com provides comprehensive climate information for every town in Spain and allows you to refine your property search according to the weather.
Visit any property on this massive property portal and click the Climate tab at the top to see average rainfall and temperature graphs for the town where that property is situated.
The data is sourced from the National Institute of Meteorology in Spain and the graphs you see represent 70,000 temperature and rainfall measurements from 4,000 weather stations throughout Spain.
An excellent resource if you are looking to buy or rent a property in Tenerife or Spain and climate is an important factor in your choice.
5. http://canalmeteo.com
Spanish weather site with excellent, detailed weather information.
The site is particularly useful if you are looking for weather forecasts for some of the smaller towns in Spain. The home page gives you an overview with a weather forecast for the whole of Spain. From here you can select a region or go directly to each town, using a drop down, alphabetical list.
Each page shows a five day forecast with the option of receiving forecast for specific towns via SMS text message.
6. www.holiday-weather.com
This easy-to-use site is clearly laid out and has daily, worldwide weather forecasts for holiday destinations. A quick link takes you straight to the Weather in Spain page, where you can search Spanish resort towns in alphabetical order, or you can use the map to go straight to the major holiday destinations in Spain. Other quick links take you directly to the top weather searches in Spain, such as Weather Majorca and Weather Tenerife.
The alphabetical town list includes all the smaller coastal towns such as Begur and Salobrena. There are easy-to-read weather updates for each town, showing Humidity, dew point, pressure and length of day. Also 2, 5 and 7 day forecasts for each town. Another useful feature is the average weather chart for each town.
7. Spain.info
This is the official website of the Spanish Tourist Office in the UK. The weather page has a snapshot view of weather throughout Spain, with quick links to temperatures and weather in the major cities.
A drop-down list allows you to select from all major towns in Spain so you can see a 5-day weather forecast for each town.
Other useful features are information on snow conditions (in Sierra Nevada, Pyrenees etc) as well as sea conditions and sunrise sunset times, and a satellite picture showing cloud cover.
8. Wikipedia
Wikipedia has an excellent overview of the geography of Spain, describing the layout of the country as well as overall climate information.
Interesting facts and figures include lowest temperature recorded (-32°C in Lago Estangento in the Pyrenees) and hottest temperature recorded (47°C in Seville and Murcia).
9. MSN Weather
The MSN weather page is really well presented and has easy to read maps showing high and low temperatures, precipitation and "cloudiness" forecast. You can also view animated maps showing weather, cloud cover and precipitation forecasts over the next 24 hours, as well as animated satellite view over next 24 hours.
The site also has some useful regional information with 10 day forecast, monthly average temperature and rainfall and even an hourly forecast showing weather predictions for the next 42 hours.
10. www.weather.com
The Weather Channel is an American weather site which allows you to view weather reports for all of Spain. Use their text search to find the town you are looking for. Weather forecasts are available for today, tomorrow, hour by hour, or for the weekend. This site has a very useful 10-Day Business Travel Forecast per town, provided in a printable format, as well as a monthly weather forecast (although this is only available for the major cities such as Madrid and Valencia) and is based on past average temperatures. It does allow you to look back and view temperatures measured day by day in previous months.
11. www.canal-esqui.com
Spanish site specialising in weather and snow reports for the ski stations of Spain. Weather information is shown for each ski station in Spain - amazingly there are currently 31 ski stations in total in Spain!
The site also has a good overview of each skiing region, giving useful information such as location, type of skiing available, number of slopes sorted by colour. You will also find links to websites for each individual ski station.
One station from each region is highlighted for having the best snow and weather conditions for skiing. Other useful information provided includes snow thickness in each resort and where the snow levels start ("cota de nieve").
12. www.rssweather.com/icao/LEGR/wx.php
If you prefer to have the weather forecast delivered direct to your own pc, this site provides you with an RSS weather feed for all of the main towns in Spain.
13. www.windfinder.com/windreports/windkarte_es.htm
For all wind surfers and sailors (or kite-fliers) in Spain, this site provides real time wind reports throughout Spain, shown on a map with wind direction and speeds. The site also provides wind forecasts, every 3 hours over 7 days on static and animated maps, as well as a map showing water temperature.
You can also set up a Wind SMS alert.
14. www.weather2travel.com/climate-guides/index.php?destination=malaga
Useful, easy-to-view climate guides with user-friendly graphics showing temperatures and information not generally found on other sites such as hours of sunshine and chance of frost, UV index and average sea temperature. The Guides provide an instant snap-shot of average weather conditions for holiday destinations in Spain for every month of the year.
You will find weather information for individual towns, sorted by Costa, Island or main city / tourist destination. You can then drill down to
see what the weather is usually like, month by month, in popular holiday destinations in Spain and the rest of the world.
15. www.spainguides.com/weather.html
Useful information about regional weather trends in Spain with reports on temperature, climate, rainfall and wind (did you know, for example, that Spain is a world leader in wind energy technologies, second only to Germany and ahead of the USA?)
Also quick links to weather reports in main cities in Spain on The Weather Channel.
16. www.navegar.com/meteo/es/
Precise forecasts, with specific information for sailors. Pay site.