• The National Weather Service ^[1] has a SOAP Web service.
• Yahoo has a weather RSS feed ^[2].
• Animaonline ^[3] is a weather API powered by Google. There are code samples and tutorial links on the project page, but I found another tutorial here ^[4].

Update:

ProgrammableWeb is currently listing 13 weather APIs ^[5] in their directory.

weather underground has xml api ^[1], i haven't used it, but judging by their website the service is quite useful in general.

Not sure if it was just free services that you were after? Free data (except NOAA) usually means that you can only use it on free sites: no subscriptions or even Google ads! It's usually quite basic (although fine for general use). Commercial-use data is more expensive and the providers don't tend to be very open about pricing etc. I've also found several sites claiming to provide commercial weather data who don't reply to contact emails. Very few data providers provide or support any programming libraries and generally just provide an XML, CSV or plain text data file -- though third-party libraries exist.

HAMweather have a raw data service ^[1], although it's not free. They provide an XML file in response to a simple HTTP call. They also provide a database dump of place names (so you can build a browseable interface) or you can query by long/lat and they support international locations. There's a Ruby api available on github (third-party, I haven't used it) and I'm sure there are other examples out there (I can't post more than one link)

HAMweather also have a PHP-based library ("HAMweather 3") for retrieving / displaying weather forecasts (free, with some conditions). The website is quite lacking in information but ping them an email and they can provide examples, pricing, documentation etc (I'm only a user of their services).

Found World Weather Online ^[1] for weather api search on google

I would suggest Wunderground It is free and the basic set of API that they provide is simple to use and developer friendly.

I have developed one Weather Forecast application based on their API for Android- http://code.google.com/p/cityweather/

I know of 1 company that has used Weather.gov ^[1]'s in the past.

PyMETAR is a python-based API that fetches and decodes METAR (text-based aviation weather) reports. I enjoy using it for my projects.

http://www.schwarzvogel.de/software-pymetar.shtml

METARs give temperature, dew point (humidity), wind, current conditions (rain, snow, fog, sunny), atmospheric pressure, etc.

Note that METARs do not include forecast information; TAFs are used for this. But PyMETAR does not handle TAFs.

Accuweather have an API ^[1] similar to HAMweather (i.e. XML files over HTTP or FTP) but again it's not free and you'll need to contact them for information/pricing

Radarmatic has a JSON API for doppler radar base reflectivity data: http://radarmatic.com/api.html

FYI: The link for PHP Weather is http://phpweather.sourceforge.net/

yahoo provides weather rss feeds that work quite well:

http://developer.yahoo.com/weather/

The Weather Channel also provides a web based API that allows searching by city or zip code. IIRC, it was pretty straightforward to use.

http://www.weather.com/services/xmloap.html

I have litter experiment with YAHOO WEATHER ^[1] API,

and it work fine following solution:

STEP 1. Get WOEID by location

http://query.yahooapis.com/v1/public/yql?q=select%20*%20from%20geo.places%20where%20text%3D%22Barrie%20CA%22&format=xml

STEP 2. Get Weather by WOEID

http://weather.yahooapis.com/forecastrss?w=%s&u=c

Completed tutorial for this solution avaialble at: http://www.anddev.org/advanced-tutorials-f21/android-weather-forecast-yahoo-weather-api-t52949.html

References:

Yahoo Weather API WOEID retrieval. ^[2]

Regards, DatNQ

I found a google weather API.

Just a simple link to access: http://www.google.co.uk/ig/api?weather=Macau (Macau is the city's name)

You can see introduction here:
http://blog.programmableweb.com/2010/02/08/googles-secret-weather-api/

Weather Underground just released a new JSON Weather API.

http://www.wunderground.com/weather/api

However to do more than token testing you will have to pay.

There is a project at Sourceforge called "PHP Weather" that makes use of METAR-data in a neat way.

Download weather widget:

I played around Google's API xml, you can try THIS:

WEATHER WEB WIDGET ^[1]

(The only problem: I was not able to fetch local time and add night icons. Give it a try and let me know! ;)

I recently develop a weather page with geolocalitation (HTML5), try this api:

http://www.theweathernow.net/api/

it uses the google weather api.

I actually created a website for a PocketPC application (StocksAndWeatherToday.com). The application was, as the name implies, an application which displayed weather to the user.

At one point in time it was the top selling application on Handango.

In its early stages it would go directly to NOAA and do screen scrapes. This was painful and required updating the app every time NOAA changed the format.

A website was created to do this so the PocketPC application could go to the website and get the data.

This greatly reduced the complexity of the application and the number of updates required. In fact, people are still using the application and it has not been updated in years.

The weather site has been around since 2005 but I have not really advertised it.

I used to have a forum but it got bombarded by spammers so I shut it down.

If interested in the site go to http://www.XmlWeather-USA.com

I just put up a simple main page which gives you an example.

Although the site implies it is only for the USA, I also put in the capability to get weather for many international cities.

RP5.US ^[1] - Weather for 243 countries including 35'747 locations in United States of America.
The service is free.
XML for example: XML ^[2]
RSS for example: RSS ^[3]
RP5.US give Cloudiness; Precipitation; Pressure; Temperature; Humidity; Wind; Sun, sunrise/sunset; Moon, moonrise/moonset; Moon, phase.