: 

National Climatic Data Center 

DATA DOCUMENTATION 

FOR 

DATA SET 9712A (DSI-9712A) 

Last Spring and First Fall Freeze Dates, 1931-1960 

December 26, 2002 

National Climatic Data Center 

151 Patton Ave. 

Asheville, NC 28801-5001 USA 
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Table of Contents 

Topic Page Number

1. Abstract................................................... 3 

2. Element Names and Definitions: ............................ 3 

3. Start Date................................................. 5 

4. Stop Date.................................................. 5 

5. Coverage................................................... 5 

6. How to order data.......................................... 5 

7. Archiving Data Center. .................................... 5 

8. Technical Contact.......................................... 6 

9. Known Uncorrected Problems................................. 6 

10. Quality Statement.......................................... 6 

11. Essential Companion Data Sets.............................. 6 

12. References................................................. 6 
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1. Abstract: The major parameters that make up the Freeze Date file are 

dates (Year, month, day) of the last occurrence in Spring and the first 

occurrence in Fall where temperatures were less than or equal to 32, 28, 20, 

and 16 degrees Fahrenheit. The selection of freeze dates was performed for 

only those US states for which revisions were made to the publication “Climate 

of the States.” As a result, only a subset of US states is represented in 

this data set. These include Arizona, California, Colorado, Delaware, Iowa, 

Maryland, Michigan, New Jersey, Oregon, Washington, and Alaska. The status of 

the other US states is unknown. 

Yearly values of the last Spring and first Fall occurrence of selected low 

temperatures were performed for the period 1931 through 1960. All years are 

not available for each station. The last Spring freeze dates were based upon 

the season January 1 through June 30 (Eg. Last spring freeze for 1931 was 

based upon the time period January 1, 1931 through June 30, 1931). The first 

Fall freeze dates were based upon the season July 1 through December 31 (Eg. 

First Fall freeze for 1931 was based upon the time period July 1, 1931 through 

December 31, 1931). 

 

2. Element Names and Definitions: 

The data are archived in a fixed length ASCII format. The total data volume 

is 2 megabytes. The data are sorted by the state number (ISTATE) as the 

primary key followed by station number (ISTATN), and year (IYEAR) as secondary 

keys. The following are FORTRAN statements and element characteristics that 

can be used to read these data: 

 Start End 

Element Type Width Column Column

ISTATE Integer 2 1 2 

ISTATN Integer 4 3 6 

IYEAR Integer 2 7 8 

ISPRNG(1) Integer 4 9 12 

ISPRNG(2) Integer 4 13 16 

ISPRNG(3) Integer 4 17 20 

ISPRNG(4) Integer 4 21 24 

ISPRNG(5) Integer 4 25 28 

 Not Used 10 29 38 

IFALL(1) Integer 4 39 42 

IFALL(2) Integer 4 43 46 

IFALL(3) Integer 4 47 50 

IFALL(4) Integer 4 51 54 

IFALL(5) Integer 4 55 58 

 Not Used 22 59 80 

Element Name Element Definition______________________ 

ISTATE Characters 1-2 

Cooperative State code number. 

Range: 02 (AZ), 04 (CA), 05 (CO), 07 (DE), 13 

(IA), 18 (MD), 20 (MI), 28 (NJ), 35 (OR), 45 

(WA), 50 (AK). See “Known Uncorrected Problems. 

ISTATN Characters 3-6 

Cooperative Station code number. 

Range 0001-9999. 
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IYEAR Characters 7-8 

This is the year of the occurrence of the last 

 Spring or first Fall freeze season within the 

 specified threshold. (E.g., Spring season for 

 1931 runs from January 1, 1931 through June 30, 

 1931. (E.g., Fall season for 1931 runs from July 

 1, 1931 through December 31, 1931) 

Range 31-60. 

LAST-SPRING-FREEZE-16 Characters 9-12 

ISPRNG(1) This is the date (month/day) of the occurrence of 

 the last Spring freeze where the temperature was 

 less than or equal to 16 degrees Fahrenheit. A 

 value of “0100" indicates the minimum temperature 

 did not reach or exceed the freeze threshold for 

 the specified year. This field is blank when 

 periods of missing minimum temperature recordings 

 made it impossible to determine the date of a 

 critical threshold temperature. 

 Month - 2 characters, Range 01-06, blank 

 Day - 2 characters, Range 01-31,00,blank 

LAST-SPRING-FREEZE-20 Characters 13-16 

ISPRNG(2) This is the date (month/day) of the 

 occurrence of the last Spring freeze 

 where the temperature was less than 

 or equal to 20 degrees Fahrenheit. 

LAST-SPRING-FREEZE-24 Characters 17-20 

ISPRNG(3) This is the date (month/day) of the 

 occurrence of the last Spring freeze 

 where the temperature was less than 

 or equal to 24 degrees Fahrenheit. 

LAST-SPRING-FREEZE-28 Characters 21-24 

ISPRNG(4) This is the date (month/day) of the 

 occurrence of the last Spring freeze 

 where the temperature was less than or 

 equal to 28 degrees Fahrenheit. 

LAST-SPRING-FREEZE-32 Characters 25-28 

ISPRNG(5) This is the date (month/day) of the 

 occurrence of the last Spring freeze 

 where the temperature was less than or 

 equal to 32 degrees Fahrenheit. 

Not Used (blank) Characters 29-38 

FIRST-FALL-FREEZE-32 Characters 39-42 

IFALL(1) This is the date (month/day) of the 

 occurrence of the first Fall freeze where 

 the temperature was less than or equal to 

 32 degrees Fahrenheit. The first Fall 

 freeze dates are chosen from the period 

 July 1 through December (E.g., the Fall freeze 

 period for 1931 runs from July 1, 1931 through 

 December 31, 1931). A value of “1232" indicates 
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 the minimum temperature did not reach or exceed 

 the freeze threshold for the specified year. 

 Month - 2 characters,Range 07-12, blank 

 Day - 2 characters,Range 01-31,32, blank 

FIRST-FALL-FREEZE-28 Characters 43-46 

IFALL(2) This is the date (month/day) of the 

 occurrence of the first Fall freeze 

 where the temperature was less than 

 or equal to 28 degrees Fahrenheit. 

FIRST-FALL-FREEZE-24 Characters 47-50 

IFALL(3) This is the date (month/day) of the 

 occurrence of the first Fall freeze where 

 the temperature was less than or equal to 

 24 degrees Fahrenheit. 

FIRST-FALL-FREEZE-20 Characters 51-54 

IFALL(4) This is the date (month/day) of the 

 occurrence of the first Fall freeze where 

 the temperature was less than or equal to 

 20 degrees Fahrenheit. 

FIRST-FALL-FREEZE-16 Characters 55-58 

IFALL(5) This is the date (month/day) of the 

 occurrence of the first Fall freeze where 

 the temperature was less than or equal 

 to 16 degrees Fahrenheit. 

Not Used (blank) Characters 59-80 

3. Start Date: 19310101. All stations do not have data beginning with 1931. 

4. Stop Date: 19601231. All stations do not have data ending with 1960. 

5. Coverage: the contiguous United States 

a. Southernmost Latitude: 18N 

b. Northernmost Latitude: 65N 

c. Westernmost Longitude: 160W 

d. Easternmost Longitude: 65W 

6. How to Order Data: 

 Ask NCDC’s Climate Services about the cost of obtaining this data set. 

 Phone: 828-271-4800 

 FAX: 828-271-4876 

 E-mail: NCDC.Orders@noaa.gov

7. Archiving Data Center: 

 National Climatic Data Center 

 Federal Building 

 151 Patton Avenue 

 Asheville, NC 28801-5001 

 Phone: (828) 271-4800. 
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8. Technical Contact: 

 National Climatic Data Center 

 Federal Building 

 151 Patton Avenue 

 Asheville, NC 28801-5001 

 Phone: (828) 271-4800. 

9. Known Uncorrected Problems: Only a subset of US states is represented in 

this data set. These include Arizona, California, Colorado, Delaware, Iowa, 

Maryland, Michigan, New Jersey, Oregon, Washington, and Alaska. The status of 

the other US states is unknown. This data set should be used with caution. 

If possible, it is recommended that a similar freeze date data set be used. 

This file contains data for 1951-1980 and is archived in DSI-9712b. 

10. Quality Statement: This data set should be used with caution. The last 

Spring and first Fall freeze dates were generated from data which contained 

missing daily minimum temperatures. It is also possible that the temperature 

data were not quality controlled prior to generating the freeze dates. 

Significant biases may have occurred because of these factors. 

If possible, it is recommended that a similar freeze date data set be used. 

This file contains data for the 1951-1980 period and is located in DSI-9712b. 

11. Essential Companion Datasets: The use of NCDC’s Station History file 

(DSI-9767) is required in order to determine metadata on each station (name, 

location, elevation, etc.). This can be accomplished by comparing the station 

number in bytes 1 through 6 of this data set with the corresponding station 

number in the Station History data set. 

12. References:

Card Deck Reference Manual 948: Freeze Data, February 1968. National Oceanic 

and Atmospheric Administration, NCDC, Asheville, NC. 3 pp.