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U.S. Climate Normals 1971-2000 Inventories Normals Station Inventory Station Selection State Inventories Divisional Inventories Surrogate Station List

Station Selection

Monthly normals are computed for as many stations as practical.  In order to be included, a station must have at least 10 years of monthly temperature data or 10 years of monthly precipitation data for each month in the period 1971-2000.  In addition, a station had to be active since January 1, 1999 OR had to be included as a normals station in the 1961-1990 normals.

In 1989, the World Meteorological Organization (WMO) prescribed standards of data completeness for stations that were subsequently included in the 1961-1990 WMO Standard Normals (WMO, 1989).  For full qualification, the thirty-year month-year sequential file had to have no more than three consecutive year-month values missing for a given month or no more than five overall values missing for a given month.  Less than fully qualified stations were included in the standard normals if they had a minimum of 10 year-month values for each month.

The requirement for a minimum of 10 years of monthly data in the 1971-2000 period assures that all stations minimally meet  standard normals requirements articulated by WMO.  Out of 7937 stations included in the 1971-2000 normals, approximately 5200 are fully qualified under the WMO guidelines, with the remaining meeting minimal requirements (except for supplemental ASOS stations; see below).  Stations meeting the full qualifications under the WMO guidelines are noted with a flag in the normals station inventory.  All stations except supplemental ASOS stations are considered official normals for the United States for the 1971-2000 period.

During the 1990s, the National Weather Service (NWS) modernized its station network, principally through the introduction of Automated Surface Observation System (ASOS) instrumentation.  As of January 2001, some 860 ASOS sites were commissioned and operational, primarily at airport locations administered by NWS or the Federal Avaiation Administration (FAA).  The introduction of ASOS has profound implications for the computation of 1971-2000 normals at impacted sites, as instrumentation and site changes, coupled with staggered implementation, calibration, and data ingesting transition schedules throughout the 1990s yielded data inhomogeneities.

To address computation of normals at ASOS locations, NCDC has grouped the 860 ASOS sites into several classes.  506 ASOS sites were cross-referenced to a Cooperative Network Identification number.  Of these, 355 stations were direct successors to previously existing stations at the same (generally airport) location.  The other 151 stations were linked to surrogate cooperative stations, meaning that a neighboring cooperative station was selected by NCDC or the ASOS program office to provide initial 1961-1990 normals for the station.

1971-2000 normals will be provided using established adjustment procedures for the 355 successor ASOS stations.  These stations will be included in the official normals release.  Adjustment strategies for the 151 surrogate ASOS stations are under review, and since these stations will have fewer than 10 years of data, they will likely be provided with the normals release as supplemental rather than official stations.  This grouping should not markedly impact the official provision of data for First-Order sites, as nearly 95% of all NWS sites are part of the 355 successor stations.

State Inventories

Data for the 1971-2000 normals are available for 7937 total stations (including 5556 temperature and precipitation stations). The locations represent sites that are part of the Cooperative Network, National Weather Service offices, and principal climatological stations in the 50 states, Puerto Rico, Virgin Islands, and Pacific Island locations.  These locations are shown in Figure 1 for (from top to bottom) the contiguous United States, Hawaii, Alaska, Puerto Rico and the Virgin Islands, and Pacific Island locations.

Figure 1
CLIM81 Station Locations

The monthly normals are published by state, with additional publications for Puerto Rico, Virgin Islands, and Pacific Islands (District of Columbia stations are included with Maryland).  The data are arranged in four tables representing temperature, precipitation, heating degree days, and cooling degree days. The locations are listed alphabetically within each table. A station locator map and cross reference index (with station name, number, type, location, and elevation) are included in the publication for each state.

State Station Maps (*.pdf format) can be accessed through Table 1.

Note that stations are classified as follows:


	First Order = Shaded Hexagon (with call sign included)
	Precipitation and Temperature = Shaded Circle
	Precipitation only = Triangle, point up
	Temperature only = Triangle, point down

Table 1
List of Station Maps (by State)

State Code - Name	State Code - Name	State Code - Name	State Code - Name	State Code - Name
01 - Alabama	11 - Illinois	22 - Mississippi	33 - Ohio	43 - Vermont
02 - Arizona	12 - Indiana	23 - Missouri	34 - Oklahoma	44 - Virginia
03 - Arkansas	13 - Iowa	24 - Montana	35 - Oregon	45 - Washington
04(a) - California (N)	14 - Kansas	25 - Nebraska	36 - Pennsylvania	46 - West Virginia
04(b) - California (S)	15- Kentucky	26 - Nevada	37 - Rhode Island	47 - Wisconsin
05 - Colorado	16 - Louisiana	27 - New Hampshire	38 - South Carolina	48 - Wyoming
06 - Connecticut	17 - Maine	28 - New Jersey	39 - South Dakota	50 - Alaska
07 - Delaware	18 - Maryland (& D.C.)	29 - New Mexico	40 - Tennessee	51 - Hawaii
08 - Florida	19 - Massachusetts	30 - New York	41(a) - Texas (Western)	66 - Puerto Rico
09 - Georgia	20 - Michigan	31 - North Carolina	41(b) - Texas (Eastern)	67 - Virgin Islands
10 - Idaho	21- Minnesota	32 - North Dakota	42 - Utah	91 - Pacific Islands

The station maps have numbers assigned to each station.  These numbers correspond to a normals station inventory, sorted by state and station name.  The format of this file is outlined in Table 2.

Table 2
Format of Normals Inventory

Begin:End Column	Description	Begin: End Column	Description
01:03	Number in State Map	67:68	Latitude (Degrees)
05:06	State Abbreviation	70:71	Latitude (Minutes)
08:13	Station ID	73:73	Latitude Hemisphere Symbol: (N)orth/(S)outh
17:21	WBAN ID	75:77	Longitude (Degrees)
26:26	X:  Maximum Temperature Flag	79:80	Longitude (Minutes)
27:27	N:  Minimum Temperature Flag	82:82	Longitude Hemisphere Symbol: (E)ast/(W)est
28:28	P:  Precipitation Flag	84:88	Elevation
32:61	Station Name	92:92	*:  First-Order Flag
63:65	ASOS Station Call Sign	99:99	+:  WMO Data Continuity Qualification Flag

Divisional Inventories

There are 344 climate divisions in the contiguous United States, with each state subdivided into as many as 10 climate divisions.  The division boundaries generally coincide with county boundaries, but frequently coincide with drainage basins in the western part of the U.S. (Guttman and Quayle, 1995).  The Climate Division Map (Adobe PDF Format) shows the climate divsions.  Table 3a lists each of the 344 climate divisions by state (Note:  There is no division 04 in Nebraska), while Table 3b lists the climate divisions for Alaska, Hawaii, Puerto Rico, the Virgin Islands, and Pacific Islands.

Table 3a
Listing of Climate Divisions for Contiguous U.S. (by State)

Table 3b
Listing of Climate Divisions for Alaska, Hawaii, and Territories

Code	Name	Code	Name	Code	Name	Code	Name
	ALASKA		HAWAII		PUERTO RICO		VIRGIN ISLANDS
5001	Southeastern	5101	Island of Kauai	6601	North Coastal	6701	St. Thomas
5002	South Coast	5102	Island of Oahu	6602	South Coastal	6702	St. Croix
5003	Southwestern Islands	5103	Island of Molokai	6603	Northern Slopes	6703	St. John
5004	Copper River	5104	Island of Lanai	6604	Southern Slopes		PACIFIC ISLANDS
5005	Cook Inlet	5105	Island of Maui	6605	Eastern Interior	9102	East of 180th Meridian
5006	Bristol Bay	5106	Island of Hawaii	6606	Western Interior	9103	Western Pacific Islands
5007	West Central	5107	Island of Kahoolawe	6607	Outlying Islands	9104	Caroline and Mariana Islands
5008	Interior Basin
5009	Arctic Drainage

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