Weather Underground

This is probably the best radar, with storm track, the ability to zoom in and a huge variety of other features. For additional radar types on the Weather Underground site, click the box above the radar image once you have selected a radar site.

Weather Underground's WunderMap - Interactive Radar

Weather Underground's WunderMap is one of the best weather tools available. It allows you to view radar data combined with weather stations, satellite data and a wide variety of other features. You can choose what you want on the map. You can zoom in as close as your house or as far away as you want.

National Weather Service Radar

This is another good site for radar. There are also regional radar views.

Intellicast Radar

This site is also good to use to view an entire regions worth of radar data. If you want to see a large part of the storm in one radar as it makes landfall, this is a great radar to do it with. The radar loops on this site are also longer which is a nice feature to use.

Weather.com - Interactive Radar

This site also has layers such as clouds, temperatures and winds.

North & South America

• Aruba (Netherlands)

  As of posting this, they link to a radar site in Venezuela. Radar is also available from Curaçao (Netherlands).

• Bahamas

  Not available as of posting this.

• Barbados

  150km, 250km and 400km range loops are available.
  
  Barbados also has an excellent Caribbean Radar Composites page. Be sure to check the imagery there if the Barbados radar has any issues:
  
  Entire Caribbean | Eastern Caribbean and part of South America | Eastern Caribbean | Northwest Caribbean

• Belize

  50km, 250km and 400km range loops are available.

• Bermuda (U.K.)

  100km, 250km and approximately 430km range loops are available. Additional imagery is also available, but for the additional options, including the approximately 430km range loop, you will need Java.

• Brazil

  There are two main sites that contain most of the radar images.
  
  Satellite and Environmental Systems Division - 240km to 250km range loops are available.
  
  Radar site from Brazil's military - 400km range loops are available.
  
  You can also view additional radars for other parts of Brazil below:
  
  Teixeira Soares, Paraná - 475km
  Cascavel, Paraná - 475km
  Quixeramobim, Ceará - 400km

• Canada

  250km range loops are available.

• Cayman Islands (U.K.)

  50km, 250km and 400km range loops are available.

• Colombia

  Colombia's radar is likely available here. (registration required) You can visit Colombia's Institute of Hydrology, Meteorology and Environmental Studies (IDEAM) here.

• Cuba (Mirror)

  Approximately 450km range loops are available.

• Curaçao (Netherlands)

  150km and 450km range loops are available.

• Dominican Republic

  No longer available as of posting this.

• El Salvador

  Various 120km radar loops are available.

• Grenada

  This imagery comes from Barbados' radar site.

• Guadeloupe (France)

  An extreme closeup radar image is available from Martinique's radar site.

• Guantanamo Bay

  Only the 124nm short range loop is available. It is sometimes out of date.

• Guyana

  150km, 250km and 400km range loops are available.

• Honduras

  250km and 500km range loops are available.

• Jamaica

  240km and 480km range loops are available at times. Make sure the time is current if imagery is available as this site sometimes has imagery that is outdated or unavailable. The link to the page also changes at times.

• Martinique (France)

  400km range loops are available from Martinique and Guadeloupe.
  
  Antilles - Radar view of most of the Lesser Antilles in the eastern Caribbean Sea.
  
  Caribbean Radar Mosaic - Lesser Antilles as well as other radar sites, when available, including the Cayman Islands, Trinidad and Tobago, Guyana and French Guiana.

• Mexico

  300km range loops are available for most locations, with some locations with a lower range, such as 240km.

• Nicaragua

  450km range loop is available.

• Panama

  Panama Canal - An approximately 120km range loop is available.
  
  Panama Meteorological Service - As of posting this, they display the Panama Canal radar site.

• Puerto Rico (U.S.)

  124nm and 248nm range loops are available.
  
  Weather Underground Long Range | NOAA Long Range

• Trinidad and Tobago

  150km, 250km and 400km range loops are available. The first two ranges have other radar products available too.

• Venezuela

  400km range loops are available. Some radar sites cover Aruba, Bonaire and Curaçao.

Other Areas

• Belgium

  240km to 300km range loops are available.

• Canary Islands (Spain)

  The maximum radar range might be 300km, but a 240km range loop is available. Radar can be viewed at Spain's meteorological service.

• Denmark

  240km range loops are available.

• Estonia

  250km range loops are available.
  
  Composite images of Nordic countries: Norway | Sweden | Finland

• Finland

  250km range loops are available.
  
  Composite images of Nordic countries: Norway | Sweden | Finland

• France

  256km range loops are available.

• Germany

  180km range loops are available.

• Iceland

  The maximum radar range is 480km, though a lesser range composite loop of the two radars is available, likely out to up to 240km.

• Ireland

  250km range loops are available. Radar data can also be viewed at the United Kingdom's Met Office.

• Latvia

  250km range loop is available. Click the image on the page to view a loop.

• Lithuania

  250km range loops are available.

• Netherlands

  The full radar range of the two radars is 320km, though a lesser range composite loop is available.

• Norway

  240km range loops are available.
  
  Composite images of Nordic countries: Norway | Sweden | Finland

• Poland

  250km range loops are available.

• Portugal

  300km range loops are available.

• Spain

  240km range loops are available.

• Sweden

  240km range loops are available.
  
  Composite images of Nordic countries: Norway | Sweden | Finland

• United Kingdom

  255km range loops are available.

Some of the European radar data comes from OPERA (Operational Programme for the Exchange of Weather Radar Information) and the WMO Weather Radar Database. (hosted by Turkey here) You can click here to view a list of WMO (World Meteorological Organization) Members, which has links to most of the world's meteorological services.