Frequently Asked Questions

At this time WeatherARC offers past (historical) surface information and upper air information for all official US National Weather Service (NWS ) sites. The surface observations are produced by National Weather Service (NWS) approved weather stations and have been quality controlled by the National Climatic Data Center (NCDC). The surface observations are obtained from the integrated surface database within NCDC. The upper air observations are produced by NWS approved weather stations and disseminated by the Integrated Global Radiosonde Archive (IGRA). Upper air observations are currently available offline. The following website http://www.ncdc.noaa.gov/oa/climate/igra/index.php provides additional information about what is contained within the IGRA database. If you would like to know exactly what we provide for the surface and upper air data you can see that list here.

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2. What is WeatherARC, what does the website do, and how is it different from other websites?

WeatherARC is designed to help you locate the weather data you need in the quickest and most cost effective manner possible and then deliver it to your email inbox. Our "Find Weather" locater allows you to quickly find the weather you need. You can find weather data for one day for one station (like the weather on your birthday) or you can find several years worth of data for several stations. Our online payment system combined with our email delivery of your data allows you to typically receive your selected data in a matter of minutes. So whether you are curious about the what the weather was on a certain day or are interested in doing some more extensive research we can provide you the data that will meet your needs.

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3. How do you deliver the data?

The data you order from us will be delivered to you via email. We will send the data to your email in the form of downloadable links.

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4. I just need to know what the weather was for that day not for each hour do you have that information?

Yes, we do have that information. It is currently available on our Find Weather Page.

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5. What is the difference between surface data and upper air data?

Official surface observations are taken approximately 2 meters (about 6 feet) above the ground. Wind information is taken from a mast approximately 10 m (33 feet) above the ground. All official surface observations must be done by using the standards contained in the FEDERAL METEOROLOGICAL HANDBOOK No. 1. "Surface Weather Observations and Reports" (FCM-h3-2005), which can be found at http://www.ofcm.gov/fmh-1/pdf/FMH1.pdf. For more information on surface observations, see the National Weather Service (NWS) surface website at http://www.weather.gov/ops2/Surface/.

As described in the FEDERAL METEOROLOGICAL HANDBOOK No. 3, official upper air observations are taken by a radiosonde, which is an instrument package carried by a balloon. The radiosonde simultaneously measures and transmits meteorological data while rising through the atmosphere from the ground to about 53,000 feet. When the wind information is processed by tracking the balloon's movement, the radiosonde instrument package is termed a rawinsonde. Rawinsonde observations of the atmosphere describe the vertical profile of temperature, humidity, and wind direction and speed as a function of pressure and height from the surface to the altitude where the sounding is terminated. Official observations must be done by using the standards contained in the FEDERAL METEOROLOGICAL HANDBOOK No. 3. "Rawinsonde and Pibals Observations" (FCM-H3-1997), which can be found at http://www.ofcm.gov/fmh3/pdf/00-entire-FMH3.pdf and http://www.ofcm.gov/fmh3/text/default.htm. For more information on upper air observations, see the National Weather Service (NWS) upper air website at http://www.srh.noaa.gov/ohx/dad/ua/uaindex.html.

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6. What weather variables do you currently provide for the surface data?

For Hourly Data:

WeatherARC currently decodes and provides the valid observation time, wind direction, wind speed, ceiling height information, visibility, temperature, dewpoint, and mean sea level pressure in English units. We provide precipitation information for rain and snow (type, frequency, and amount) in Metric units. (Convert units) Additional items such as present weather, minimum and maximum temperatures, pressure tendency, a description of the cloud cover, wind gusts, and other significant weather are provided in the remarks section of the data but are not decoded.

For Daily Data:

WeatherARC currently decodes and provides the average temperature, average dewpoint, average wind speed, maximum sustained wind speed, wind gust, average station pressure, maximum temperature, minimum temperature, and amount of precipitation.

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7. What weather variables do you currently provide for the for upper air data?

WeatherARC currently decodes and provides the release time of the balloon, the date and time the observation is valid, the number of levels, designation between the levels as to whether they are major or minor levels. For each level we provide the height, temperature, dewpoint, wind speed, wind direction, and atmospheric pressure all in Metric units. (Convert units) *Note that upper air data is only available offline currently.

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8. How often are surface observations taken?

For Hourly Data:

For full-time surface observation stations a complete observation are taken once every hour. At full-time stations, observations are also taken and available in between hours if certain "special" events occur, such as the starting or stopping of rain. There are also limited surface observing sites that take hourly observations during certain times of the day as needed.

For Daily Data:

The data is compiled once daily.

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9. How often are upper air observations taken?

During daylight savings:

At the majority of upper air stations, upper air observations are taken twice each day, 0000 UTC (8:00 PM EDT) and 1200 UTC (8:00 AM EDT). A few stations also take observations at 0600 UTC (2:00 AM EDT) and 1800 UTC (2:00 PM EDT).

During non-daylight savings:

At the majority of upper air stations, upper air observations are taken twice each day, 0000 UTC (7:00 PM EDT) and 1200 UTC (7:00 AM EDT). A few stations also take observations at 0600 UTC (1:00 AM EDT) and 1800 UTC (1:00 PM EDT).

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10. What is UTC time?

UTC stands for Universal Coordinated Time and was previously known as Greenwich Mean Time (GMT). Corresponds to the time at the Prime Meridian (0° longitude) and operates off of a twenty four hour clock. UTC is commonly used in meteorology as the standard reporting time to allow for consistency in weather reporting. Observations are taken and recorded based on the UTC time they occurred. With the presence of so many time zones across the globe the use of UTC time makes it easy to compare different weather observations from different locations and not have to worry about time conversions. Here are tables to convert UTC time to EST, CST, MST, PST, AST, and HST.

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11. How long does it take for the weather observations to become available?

WeatherARC provides surface observations with approximately a 2-3 day time lag. Currently surface observations are available up to and including the 2010 calendar year.

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12. What is the quality assurance of the data?

The observations are all official observations taken by National Weather Service (NWS) approved locations and observers. Detailed quality control is performed on all observations, at the National Climatic Data Center (NCDC), ensuring the data you receive is of the highest accuracy. Each variable within the surface data and the upper air data undergoes several levels of quality control. The variables are compared to the averages and climatology of that station to check for possible errors. For a more complete guide to the quality control performed on the surface data you can go to the surface data quality control document courtesy of NCDC. For a more complete guide to the quality control performed on the upper air data you can go to the upper air quality control document courtesy of NCDC.

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13. What is the period of record for most stations?

The period of record varies among the available stations. There are several stations that have data going back as far as the early 1930's. However a majority of stations did not start reporting and recording observations until the 1950's, 1960's, and 1970's. Some stations, for one reason or another (with some of the reasons listed in the question below) do not have data for certain years or they have ceased to provide data for the more recent years as those stations may have closed. We, at WeatherARC, do our best to provide you with the most complete dataset available for every station.

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14. How complete is the observational database (in time) for a given station?

Some stations have very complete records (99% or better reporting rate), while others have significant gaps in the observations over their period of record. There are several factors that impact the completeness of the observations at a station. Some of these factors are:

The time period that the station has been in operation. Because of many factors observing sites are moved, added, or even closed. If the move of the station is not far, it will have the same name as the old location. So, if the exact location of an observation is important to you, you may need the station history information for that site (station history information courtesy of NCDC).

Whether the station is full or part time is also important. Part time stations will likely have fewer observations as there may not always be someone there to monitor the weather station and take necessary measurements.

Missing observations. For all stations there will be an occasional missing observation due to a variety of factors (The weather station may be broken).

Weather observations from earlier years tend to contain fewer elements as not as many weather elements were measured or sampled at that time.

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15. How many weather stations do you have data for?

There are approximately 4200 surface stations and 120 upper air stations that we provide data for. Some stations are now or have been closed in the past and some were part time observing stations so not all stations have a continuous data record.

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16. How dense is the spatial coverage of the observing network for surface and upper air observations?

The surface observational network is more dense in highly populated areas, but in general in the U.S. they are spaced between 25 - 100 miles apart. In the U.S. upper air stations are spaced approximately 200 - 300 miles apart.

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17. What are the official definitions of the various weather variables and terms provided in your dataset?

For a list of the definitions for the most common meteorology terms go to:

Weatherarc's Weather Terms page

For a more complete list of operational and scientific meteorological definitions try:

United States National Weather Service Glossary: http://www.weather.gov/glossary/

American Meteorological Society Glossary of Meteorology: http://amsglossary.allenpress.com/glossary/

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18. What is the difference between current, historical, and climatological data?

Current data refers to the latest available observational data, typically from the last hour. Historical data refers to observations from the past. Climatological data is the result of performing some statistical operation on a given time period (history) of observations. That climatological time period can be as short as one day, such as the mean, maximum and minimum temperature for a given day or it can be as long as several decades, such as a 50-year average rainfall amounts. Climatological data is typically a report of the average weather conditions (temperatures, precipitation, wind speed, etc...) that occurred in a given location ocer the past 30 years.

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19. What data formats do you currently support?

WeatherARC currently provides data files in .html (viewable in internet browser), .csv (comma separated value), .zip, and .tgz (tar files compressed with gunzip) formats. However we can provide the data to you in almost any format you need.

The .csv file is easily viewed in a spreadsheet program like Excel. Here is a sample of each data format, including some formats currently only available by contacting us. If we do not have a format you desire please contact us and we will do our best to assist you.

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20. What are the schema's for the upper air and/or surface data “.xml” files?

Data is no longer actively being provided in xml format. Please inquire (1-518-283-5322) if you desire this data.

Here is the upper air data schema.

Here is the surface data schema.

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21. I am desiring additional analysis and understanding of my data, how do I obtain assistance?

WeatherARC will provide consultation services for your data, if requested. We can create graphs and other charts and spreadsheets of your data as needed for your project. Our consulting rate is $60.00 (US Dollars) per hour. If you desire such service or we can be of additional assistance to you please contact us.

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22. I need certified weather data, how can I obtain it?

Please check out our Certified Data Page for information about obtaining certified weather data.

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Purchasing Questions

23. What is the cost of the data and what are your accepted methods of payment?

Please go to the pricing table page to the prices of all the products we sell. We accept all major credit cards for online payment including American Express^®, Discover^®, Visa^®, and Mastercard^®. We also have the option to pay with your PayPal^® account. Simply click on the PayPal^® icon in the red mini shopping cart on the Find Weather Page or on the Checkout with PayPal^® icon in the full shopping cart. You will be required to login to your PayPal^® account if you are paying via PayPal^®.

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24. What is the maximum amount of data that can be purchased online through your website?

We can currently only handle a maximum purchase of 75000 individual observations worth of weather data (approximately 2-3 years worth of hourly data) if you will be purchasing through our website. We can handle larger data requests offline, please contact us and we will assist you in purchasing your data.

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25. How do I purchase data if I live outside of the United States?

You will need to either use your PayPal account or contact us via telephone at 1-518-283-5322 (Alt. Number 1-518-283-5169) and we will process your order over the phone. We will require your name, address, email address, phone number, and credit card information if you will be purchasing over the phone.

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General Questions about the WeatherARC Website

26. How do I login to avoid retyping contact information when I make a purchase?

On the homepage (and throughout the website) there is a link in the upper right corner that says login. Click on that link and click create an account. Enter your information into the fields and then click add account. You should then be able to login by entering your email address and password. Once you login your contact information should then display when you proceed to the checkout. Logging in is not necessary if you will be using the PayPal^® feature to make a purchase. Note that credit card information is not saved in the login section. That information must be re-entered each time. When making future purchases you can login on the homepage and when you arrive at the checkout your saved information will be displayed.

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27. How do I change my contact data and/or password?

Login to your account; there is a link in the upper right hand corner (throughout the website) that says login. The upper right hand corner should now say Edit My Account and Logoff. Click on Edit My Account. Enter in your new information and click the update account button below. That will save your new address information. To change your password login as above and click on edit my account, in the upper right hand corner, after you login. Below the box that says city click on change password. Type in your new password in both boxes and click change password.

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28. How do I remove items from the shopping cart?

There are three ways to do this. The first way is to click on the shopping cart icon located on the top banner of the page. You can click the remove button next to each item if you want to only remove certain items or you can click empty cart to remove all the items in your shopping cart. The second way is if you are located on the checkout page scroll to the bottom of the page and under the confirm order button click on edit shopping cart. You can click remove next to each item if you want to only remove certain items or you can click empty cart to remove all the items in your shopping cart. The third way is to click on the shopping cart link at the top of the red mini shopping cart that displays on the Find Weather Page after you have added items to the cart. You will then be taken to the shopping cart page where you can either remove single items or empty the cart as noted above with the previous two options.

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29. Where do I go to submit general comments or questions?

You can click contact on the top banner on the page (all the way to right). You can then enter your comment in the box below the email box. Also, on the checkout page of the website there is a comment box under the zip code box. If you are making a purchase and not using your PayPal account and would like to enter comments you can insert them there. Your comments will be sent out when you click confirm order. If you are paying with your PayPal account you can click contact on the top banner on the page (all the way to right) on our site, not on the PayPal site. You can then enter your comment in the box below the email box.

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WeatherARC Privacy and Terms of Service

30. What is your privacy policy and how can I get a copy of it?

WeatherARC respects customer privacy. We will not disclose your contact information to third parties. This is WeatherARC's privacy policy.

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31. What are the WeatherARC terms of service?

In consideration of you paying us the fee, we will grant you a non-exclusive non-transferable permit for you to use the service to view print and/or use the data obtained from WeatherARC. The specific details of this are disclosed in our Terms of Service Agreement.

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Troubleshooting

If you have a problem go to the WeatherARC Troubleshooting Page

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