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Data Download Documentation

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WeatherSpark offers a for-fee data download service. The data is delivered as CSV (comma separated value) files, which is broadly compatible with most spreadsheet software. Data is available in three different time scales: hourly, daily, and monthly. Each time scale includes a different list of data fields. This page documents what data is included in the download, and discusses how the data is collected and collated.

Preview The Data Before You Download.

The data in the download is drawn from the same source that powers WeatherSpark's Interactive Weather Dashboard. Weather stations occassionally experience outages, and it is possible though unlikely that data from a weather station may have been recorded but didn't make it into our archive for some reason. Therefore, before making a purchase, please inspect the data in the Dashboard to make sure that we have the data you are looking for.

A lot of stations do not report Precipitation Amount, especially outside the US. If that is the data series you're looking for, then please turn on the Precipitation Amount graph when reviewing the stations you're interested in to make sure they have this data before making a purchase. You can also review the precipitation section of the station's history report.

The tables below list what data is reported for each time scale. Just because a field is listed below does not mean that it will have an entry for a given weather station at a given time. For example, we have columns for up to six different cloud layers, each with its own height and coverage fraction, but in the vast majority of cases, there are only one or two cloud layers reported. Likewise for the weather codes.

Time Zones

WeatherSpark fundamentally operates in local time, since that is the time frame in which the people who experience the weather operate. This means that when talk about a day, we mean a day in local time, spanning from midnight to midnight, as experienced by people living there at the time. Likewise for months. Universal time (UTC) is also really important in many applications, so in the hourly report we include the corresponding UTC time stamp along with the local time. WeatherSpark takes full account of daylight savings time by utilizing the same technology that powers the AskGeo Geospatial Information Service.

Time Stamps

A large portion of the world's weather stations are located at airports. Most of these report weather conditions once an hour, typically near—though rarely exactly at—the top of the hour. As is common in the industry, we report our measurements by hour, omitting the minutes before or after the hour that the measurement actually took place. If you have an application where knowing the minute of the measurement is important, please email us at feedback@__remove_this_part__weatherspark.com and we'll do our best to help you.

Cloud Coverage

Many but not all weather stations report the degree to which the sky is covered by clouds. There are six possible cloud cover categories: clear, most clear, partly cloudy, mostly cloudy, and overcast. When working with cloud coverage data, please consider the following points:

  • Modern automated weather stations measure cloud coverage using laser ranging technology that produces accurate and consistent measurements, but older stations rely on estimates made by the person manning the station.
  • Starting in the mid 1990s, the National Weather Service in the United States has been upgrading to use automated weather stations.
  • Some stations only report during the operating hours of the host airport, leading to systematically missing data at night.
  • Outside the United States it is also common practice to only report cloud coverage if it is significant from an aviation perspective, leading to large sections of missing data.
Data from the United States from before 1996 and all data from stations outside the United States should be subjected to greater scrutiny. Please see the Cloud Coverage and Present Weather Codes Page for further details.

Weather Codes

One of the richest parts of the data are the present weather reports. These record things like rain, snow, fog, thunderstorms, blowing dust, or smoke in the air. WeatherSpark's weather reports utilize a custom-built weather coding system that we believe to be the best in the industry. We have carefully constructed a numerical coding system for describing observed weather phenomena that contains literally thousands of individual codes, each with an accurate but brief description, and a corresponding icon code. The icon code, of which there are presently 17, is a condensed and simplified weather code typically used for statistical or display purposes. You can learn more about Weather Spark's weather codes on the Cloud Coverage and Present Weather Codes Page.

Special Reports

Sometimes when notable weather is occuring, additional reports might be issued at other times. When considering more than one report, we take the report that is closest to the top of the hour as our report for that hour. There are three exceptions to that rule.

First, since present weather observations (e.g., rain, snow, and thunderstorms) are so important, and since we are able to include more than one such observation in our hourly reports, we merge all such observations from all the reports within plus or minus thirty minutes of the top of the hour, up to a maximum of six codes. If there are more than six codes, we keep the more severe codes. For example, we'd drop a fog report before we'd drop a rain report, and we'd drop a rain report over a thunderstorm report. There are rarely more than six codes associated with a given hourly report, so this is rarely an issue.

Second, in the United States the regular hourly reports include a measure of how much liquid equivalent precipitation was collected in the preceding hour. The special reports either don't include a measure of liquid precipitation, or report the quantity collected since the last regular or special report. Since our reporting interval is one hour, we always take the liquid precipitation measurement from the regular hourly report, never from a special report, even if that special report is closer to the top of the hour.

Finally, if for whatever reason the report that is closest to the top of the hour doesn't include a field that is included in another report, then we fall back on the other report rather than leaving it empty.

Recent Records

WeatherSpark draws its historical data and current conditions from two main sources. The first is used to provide the current conditions and the recent past. The second involves a much more rigorous quality control process and is consequently delayed by a few days. As data from the second more accurate source becomes available, we ingest it into our system an overwrite the data from the real-time feed. This means that you may get records that come from the less rigorously vetted real-time source if you are looking at records that are less than a month old. For most stations and times the two data sources agree perfectly.

Hourly Data

The hourly data is reported in local time and UTC and includes a wide varity of measurements.

NameDescriptionUnits/Type
Year LocalThe year of the measurement in local time. year
Month LocalThe month of the measurement in local time. month (1 - 12)
Day LocalThe day of the measurement in local time. day (1 - 31)
Hour LocalThe hour of the measurement in local time. hour (0 - 23)
Year UTCThe year of the measurement in UTC. year
Month UTCThe month of the measurement in UTC. month (1 - 12)
Day UTCThe day of the measurement in UTC. day (1 - 31)
Hour UTCThe hour of the measurement in UTC. hour (0 - 23)
Cavok ReportedWhether or not the station reported 'CAVOK' ('Ceiling And Visibility OK'), which is used outside the US for sky conditions that are not a problem for flying. This often corresponds to clear skies, but not always. {0, 1}
Cloud Ceiling (m)NOAA's value for the 'cloud ceiling' is usually the height of the lowest layer of clouds that is reported as 'broken', 'overcast' or 'obscuration' (typically meaning at least five eighths of the sky is covered). However, in some cases ceiling values reported by NOAA do not match this rule when compared to the individual cloud layer reports.m
Cloud Cover FractionThe fraction of the sky covered by clouds (the maximum fraction of the coverage fractions of the reported cloud layers. [0, 1]
Cloud Cover Fraction 1The cloud coverage fraction of the first cloud layer. [0, 1]
Cloud Cover Fraction 2The cloud coverage fraction of the second cloud layer. [0, 1]
Cloud Cover Fraction 3The cloud coverage fraction of the third cloud layer. [0, 1]
Cloud Cover Fraction 4The cloud coverage fraction of the fourth cloud layer. [0, 1]
Cloud Cover Fraction 5The cloud coverage fraction of the fifth cloud layer. [0, 1]
Cloud Cover Fraction 6The cloud coverage fraction of the sixth cloud layer. [0, 1]
Cloud Height (m) 1The height of the first cloud layer. m
Cloud Height (m) 2The height of the second cloud layer. m
Cloud Height (m) 3The height of the third cloud layer. m
Cloud Height (m) 4The height of the fourth cloud layer. m
Cloud Height (m) 5The height of the fifth cloud layer. m
Cloud Height (m) 6The height of the sixth cloud layer. m
Dew Point (C)The dew point. C
Humidity FractionThe relative humidity expressed as a fraction. [0, 1]
Precipitation One Hour (m...The liquid equivalent quantity of precipitation (in mm) measured during the preceding hour. mm
Pressure Altimeter (mbar)The altimeter setting (in mbar) given in the weather report. mbar
Pressure Sea Level (mbar)The sea level pressure mbar
Pressure Station (mbar)The station pressurembar
Snow Depth (cm)The snow depth (not reported for all stations, rarely measured outside the US, typically reported every six hours when present). cm
Temperature (C)The air temperature. C
Visibility (km)The visibility. km
Weather Code 1The first weather code (an integer code representing some type of weather phenomenom). integer
Weather Code 1/ Descripti...The description of the first weather code. string
Weather Code 2The second weather code. integer
Weather Code 2/ Descripti...The description of the second weather code. string
Weather Code 3The third weather code. integer
Weather Code 3/ Descripti...The description of the third weather code. string
Weather Code 4The fourth weather code. integer
Weather Code 4/ Descripti...The description of the fourth weather code. string
Weather Code 5The fifth weather code. integer
Weather Code 5/ Descripti...The description of the fifth weather code. string
Weather Code 6The sixth weather code. integer
Weather Code 6/ Descripti...The description of the sixth weather code. string
Weather Code Most Severe ...The integer icon code corresponding to the most severe of the weather codes in this report. integer
Weather Code Most SevereThe most severe weather code in this report. integer
Weather Code Most Severe ...The description of the most severe weather code in this report. integer
Wind Direction (degrees)The wind direction. degrees
Wind Gust (m/s)The wind gust speed. m/s
Wind Speed (m/s)The wind speed. m/s

Daily Data

NameDescriptionUnits/Type
Year LocalThe year of the measurement in local time. year
Month LocalThe month of the measurement in local time. month (1 - 12)
Day LocalThe day of the measurement in local time. day (1 - 31)
Cloud Ceiling (m) / MeanThe mean cloud ceiling height of this day's hourly reports. m
Cloud Cover Fraction / Fr...The fraction of hourly reports where the cloud coverage fraction was not reported. [0, 1]
Cloud Cover Fraction / Fr...The fraction of hourly reports where the sky was reported as 'clear'. [0, 1]
Cloud Cover Fraction / Fr...The fraction of hourly reports where the sky was reported as having 'few' clouds (1/8 cloud coverage or less) . [0, 1]
Cloud Cover Fraction / Fr...The fraction of hourly reports where the sky was reported as having 'scattered' clouds (2/8 - 4/8 cloud coverage). [0, 1]
Cloud Cover Fraction / Fr...The fraction of hourly reports where the sky was reported as having 'broken' clouds (5/8 - 7/8 cloud coverage). [0, 1]
Cloud Cover Fraction / Fr...The fraction of hourly reports where the sky was reported as 'overcast', or 'obscured'. [0, 1]
Cloud Cover Fraction / Me...The median cloud coverage fraction of this day's cloud coverage reports. [0, 1]
Dew Point C / HighThe highest dew point in this day's hourly reports. C
Dew Point C / LowThe lowest dew point in this day's hourly reports. C
Humidity Fraction / HighThe highest relative humidity in this day's hourly reports. [0, 1]
Humidity Fraction / LowThe lowest relative humidity in this day's hourly reports. [0, 1]
Humidity Fraction / MeanThe mean relative humidity of the hourly reports. [0, 1]
Precipitation One Hour (m...The mean quantity of liquid equivalent precipitation from the day's hourly reports. mm
Precipitation One Hour (m...The sum of the liquid equivalent precipitation from the day's hourly reports. mm
Weather Codes / Precipita...The count of this day's hourly reports that include at least some precipitation or thunderstorm report. integer
Weather Codes / Drizzle C...The count of this day's hourly reports in which drizzle was the most severe weather reported. integer
Weather Codes / Rain Slig...The count of this day's hourly reports in which slight rain was the most severe weather reportedinteger
Weather Codes / Rain Mode...The count of this day's hourly reports in which moderate rain was the most severe weather reportedinteger
Weather Codes / Rain Heav...The count of this day's hourly reports in which heavy rain was the most severe weather reportedinteger
Weather Codes / Snow Slig...The count of this day's hourly reports in which slight snow was the most severe weather reportedinteger
Weather Codes / Snow Mode...The count of this day's hourly reports in which moderate snow was the most severe weather reportedinteger
Weather Codes / Snow Heav...The count of this day's hourly reports in which heavy snow was the most severe weather reportedinteger
Weather Codes / Thunderst...The count of this day's hourly reports in which a thunderstorm was the most severe weather reportedinteger
Weather Code Most Severe ...The icon code of the most severe weather reported in this day's hourly reports. Returns the icon for 'no weather' for days with at least 23 of 24 reports indicating no weather at all. This code is intended as the best single-icon characterization of this day's weather. integer
Pressure Altimeter (mbar)...The mean altimeter setting from this day's hourly reports. mbar
Snow Depth (cm) / MeanThe mean snow depth from this day's snow depth reports, if available. cm
Temperature C / HighThe highest temperature in this day's hourly reports. C
Temperature C / LowThe lowest temperature in this day's hourly reports. C
Visibility (km) / MeanThe mean visibility from this day's hourly reports. km
Wind Direction (degrees) ...The angular mean wind direction from this day's hourly reports. degrees
Wind Gust (m/s) / MaxThe highest reported wind gust speed for the day. m/s
Wind Speed (m/s) / HighThe highest reported wind speed among the hourly reports for the day. m/s
Wind Speed (m/s) / LowThe lowest reported wind speed among the hourly reports for the day. m/s
Wind Speed (m/s) / MeanThe mean wind speed among the hourly reports for the day. m/s

Monthly Data

NameDescriptionUnits/Type
Year LocalThe year of the measurement in local time. year
Month LocalThe month of the measurement in local time. month (1 - 12)
Cloud Ceiling (m) / MeanThe mean of this month's daily mean cloud ceiling heights. m
Cloud Cover Fraction / Fr...The fraction of hourly reports where the cloud coverage fraction was not reported. [0, 1]
Cloud Cover Fraction / Fr...The fraction of hourly reports where the sky was reported as 'clear'. [0, 1]
Cloud Cover Fraction / Fr...The fraction of hourly reports where the sky was reported as having 'few' clouds (1/8 cloud coverage or less) . [0, 1]
Cloud Cover Fraction / Fr...The fraction of hourly reports where the sky was reported as having 'scattered' clouds (2/8 - 4/8 cloud coverage). [0, 1]
Cloud Cover Fraction / Fr...The fraction of hourly reports where the sky was reported as having 'broken' clouds (5/8 - 7/8 cloud coverage). [0, 1]
Cloud Cover Fraction / Fr...The fraction of hourly reports where the sky was reported as 'overcast', or 'obscured'. [0, 1]
Cloud Cover Fraction / Me...The median of this month's daily median cloud coverage values. [0, 1]
Dew Point C / Mean Daily ...The mean value of this month's daily high dew point. C
Dew Point C / Mean Daily ...The mean value of this month's daily low dew point. C
Humidity Fraction / Mean ...The mean of this month's daily high relative humidity. [0, 1]
Humidity Fraction / Mean ...The mean of this month's daily low relative humidity. [0, 1]
Humidity Fraction / MeanThe mean of this month's daily mean relative humidity. [0, 1]
Precipitation One Hour (m...The mean quantity of liquid equivalent precipitation from the month's hourly reports. mm
Precipitation One Hour (m...The sum of the liquid equivalent precipitation from the month's hourly reports. mm
Weather Codes / Precipita...The mean number of hourly reports per day that include at least some precipitation or thunderstorm report. [0, 24]
Weather Codes / Drizzle C...The mean number of hourly reports per day in which drizzle was the most severe weather reported. [0, 24]
Weather Codes / Rain Slig...The mean number of hourly reports per day in which slight rain was the most severe weather reported[0, 24]
Weather Codes / Rain Mode...The mean number of hourly reports per day in which moderate rain was the most severe weather reported[0, 24]
Weather Codes / Rain Heav...The mean number of hourly reports per day in which heavy rain was the most severe weather reported[0, 24]
Weather Codes / Snow Slig...The mean number of hourly reports per day in which slight snow was the most severe weather reported[0, 24]
Weather Codes / Snow Mode...The mean number of hourly reports per day in which moderate snow was the most severe weather reported[0, 24]
Weather Codes / Snow Heav...The mean number of hourly reports per day in which heavy snow was the most severe weather reported[0, 24]
Weather Codes / Thunderst...The mean number of hourly reports per day in which a thunderstorm was the most severe weather reported[0, 24]
Weather Code Most Severe ...The icon code of the most severe of the month's daily most severe icon code ('weatherCodeMostSevere/IconCode'). integer
Pressure Altimeter (mbar)...The mean of this month's daily mean altimeter setting. mbar
Snow Depth (cm) / MeanThe mean of this month's daily mean snow depth. cm
Temperature C / Mean Dail...The mean value of this month's daily high temperature. C
Temperature C / Mean Dail...The mean value of this month's daily low temperature. C
Visibility (km) / MeanThe mean visibility from this month's daily mean visibility. km
Wind Direction (degrees) ...The angular mean of this month's daily angular mean wind direction. degrees
Wind Gust (m/s) / MaxThe highest reported wind gust speed for the month. m/s
Wind Speed (m/s) / HighThe highest reported wind speed among the hourly reports for the month. m/s
Wind Speed (m/s) / LowThe lowest reported wind speed among the hourly reports for the month. m/s
Wind Speed (m/s) / MeanThe mean of this month's daily mean wind speed. m/s