FINAL Fall 2013 Frost/Freeze Recap

Fall 2013 Frost/Freeze Recap: Considering that "first fall-freeze dates" across the NWS Hastings coverage area in South Central Nebraska and North Central Kansas can sometimes vary by 5 weeks or more from one year to another, it can be difficult to put one particular season into perspective. However, when taking into account 30-year averages of the first occurrence of 32° and 28° (or colder), the majority of the NWS Hastings coverage area met these temperature thresholds generally 1-3 weeks later than average during Fall 2013, especially with regard to the first "hard freeze" of 28°-or-colder. In fact, several locations notched their latest hard freeze in at least the last 15 years, and in some cases as many as FIFTY years! Needless to say, this was in sharp contrast to one year ago in Fall 2012, when much of the area realized the first freeze/hard freeze of the season 2-3 weeks earlier than average. 

Here is a brief summary of the progression of sub-freezing temperatures across the area during Fall 2013 (based primarily on NWS cooperative observer data): The first known sub-freezing readings of the season (32° or colder) occurred in a few northern/western spots such as Ord and Edison on Oct. 7th. Slowly but surely, other portions of the area dropped below the freezing mark for the first time on mornings such as Oct. 13th, 16th, 18th, with far southeast locations such as Hebron and Beloit finally joining in on the 19th. As for the first hard freeze of the season (28° or colder), far northern locations such as Ord airport reached this mark as early as Oct. 13th, but this was a notably early exception. On Oct. 21st, other limited areas scattered throughout the area joined in on the first hard freeze, including Central City, York, Franklin, Burr Oak KS and two miles southwest of Alton KS. During the final week of October, other sites such as Osceola and Cambridge also notched the first hard freeze of the season. However, for many southern/eastern portions of the coverage area, it took until sometime between Nov. 5-12 to finally pound the nail in the coffin on the first hard freeze of the fall. For those places such as Hebron, Beloit KS and Smith Center KS that held off until Nov. 12th, the first hard freeze came with authority, as nearly the entire coverage area plunged to 15°-or-colder on that morning.

Please refer to the table located farther down the page for a wealth of information on average frost/freeze dates along with Fall 2013 results for 13 chosen locations across the NWS Hastings coverage area. Based on the results in the table, here are just a few "highlights" involving locations that strayed at least 10 days from average first frost/freeze dates:

- First occurrence of 28° (hard freeze) or lower:
 
Beloit KS (Nov. 12) was 18 days later than average, and the latest since 1963...50 years ago!
Smith Center KS (Nov. 12) was 24 days later than average, and the latest since 1964...49 years ago!
Hebron (Nov. 12) was 24 days later than average, and the latest since 1978
Hastings NWS Office (Nov. 11) was 24 days later than average, and the date tied for the latest since 1998 
(please note that Hastings airport did not have as late of a hard freeze as the NWS Office, reaching 28° on Nov. 2)
Grand Island airport (Nov. 5) was 22 days later than average, and the latest since 1998
Kearney airport (Nov. 6) was 22 days later than average, and the latest since 1998


- First occurrence of 32° (freezing) or lower: 
Greeley (Oct. 13) was 15 days later than average, and tied for the latest since 1997



Before continuing, here are a few definitions:

- Frost occurs when there is a solid deposition of water vapor from the air. Frost will form when solid surfaces are cooled below the dew point. An air temperature range of 33-36° along with very light winds are usually needed to initiate frost formation. Minor damage is possible to some plants. One must keep in mind that a frost is not guaranteed at these temperatures if moisture in the air is lacking. The range of average dates for the first occurrence of fall frost across most of south central Nebraska and north central Kansas is between Sep. 23 - Oct. 7.

- Freeze occurs when the air temperature drops to 32° or lower. A freeze will result in significant damage to many unprotected plants, especially if the temperature remains at the freezing mark for a few hours. The range of average dates for the first freeze of the fall across most of south central Nebraska and north central Kansas is between Sep. 28 - Oct. 16.

- Hard Freeze occurs when the temperature reaches 28° or lower for at least a few hours. It usually means that many types of plants and most seasonal vegetation will be destroyed. The range of average dates for the first hard freeze of the fall across most of south central Nebraska and north central Kansas is between Oct. 5 - Oct. 25.



Detailed Fall Frost/Freeze Table and Climatological Maps:

Below is a table and set of maps, primarily focused on average dates for reaching particular temperature frost/freeze thresholds. However, there is often tremendous variation from year-to-year and between any given location across the area (see bottom of page for details on unusually early freeze in September 1974).

Examining the table below, here are a few things to consider:

- The first column lists 9 chosen locations in south central Nebraska and 4 in north central Kansas with long histories of being NWS Cooperative Observer sites (except for Grand Island and Hastings airports, which are automated systems). This is just a small sampling of dozens of observing locations within the NWS Hastings coverage area, and these sites are generally organized from north to south down the column.

- The second column shows the average date of the earliest observance of 36, 32, and 28 degree temperatures during the most recent 30-year period from 1983-2013. Please note that differences in average freeze dates between these locations are NOT purely a function of "north versus south", but also depend on a variety of factors including local terrain. For example, Alton, KS, in Osborne County is typically prone to earlier freezes in the fall than some locations farther north, thanks to efficient cold air drainage along the South Fork Solomon River valley.

- The third and fourth columns reveal the earliest first freeze date and latest first freeze date (32 degrees or colder) observed during the past 30 years, covering the period 1983-2013. It is readily apparent that the phrase "average freeze date" is quite relative, as most sites have a 5-7 week difference between the earliest and latest dates. For the majority of locations, the earliest last freeze during the past 31 years occurred between Sep. 15th-22nd in years such as 1991 and 1993. On the opposite spectrum, for many locations the latest freeze during the past 31 years occurred between Oct. 23th- Nov. 4th in years such as 1997 and 1998.

- The final column on the right reveals the date that 36, 32 and 28-degree thresholds were first met THIS FALL within the area. A blue-shaded date indicates a location that reached a temperature threshold more than 7 days before the average date, while red-shaded dates indicates that this threshold was met more than 7 days after the average date.

 Climatological Data For South Central Nebraska and North Central Kansas
(all averages based on 30-year observations from 1983-2012)

 

Average First 
Date of...

36 Degrees
32 Degrees
28 Degrees

Earliest Date 
1983-2013 of...

32 Degrees
or Colder 

Latest Date 
1983-2013 of...

32 Degrees
or Colder 

First Fall 2013  
Occurence of...

36 Degrees
32 Degrees
28 Degrees

 Greeley

Sep. 23
Sep. 28
Oct. 5

Sep. 15,1993 

Oct. 13, 2013
Oct. 13,1997

Sep 21 (34°)
Oct. 13 (30°)
Oct. 18 (26
°)

 Osceola

Sep. 30
Oct. 8
Oct. 13

Sep. 19, 1991

Nov. 3, 1998

Oct. 17 (35°)
Oct. 18 (30
°)
Oct. 24 (28°)

 Kearney Airport
(NWS Observer)

Sep. 26
Oct. 5
Oct. 15

Sep. 19, 1991

Oct. 25, 1997 

Oct. 5 (36°)
Oct. 16 (32
°)
Nov. 6 (28°)

 Grand Island
 (airport)

Sep. 29
Oct. 8
Oct. 14

 Sep. 19, 1991

 Oct. 26, 2007

Oct. 16 (36°)
Oct. 17 (32
°)
Nov. 5 (28°)

 York

Oct. 2
Oct. 10
Oct. 20

 Sep. 19, 1991

Nov. 4, 1998

Oct. 7 (36°)
Oct. 17 (32
°)
Oct. 21 (27°)

 Cambridge

Sep. 24
Oct. 2
Oct. 12

Sep. 15, 2008

 Oct. 25, 1997

Oct. 7 (36°)
Oct. 16 (29°)
Oct. 25 (28°)

 Holdrege

Oct. 2
Oct. 9
Oct. 20

Sep. 20, 1991

Nov. 4, 1998

Oct. 5 (34°)
Oct. 16 (29
°)
Oct. 21 (26°)

 Hastings
(NWS Office/airport)

Sep. 29
Oct. 8
Oct. 18

Sep. 20, 1991

 Nov. 3, 1998

Oct. 16 (33°)/Oct. 16 (33°)
Oct. 18 (31°)/Oct. 17 (31
°)
Nov. 11 (21°)/Nov. 2 (28°)

 Hebron

Sep. 30
Oct. 10
Oct. 19

 Sep. 19, 1991

 Oct. 26, 2007

Oct. 12 (36°)
Oct. 19 (30°)
Nov. 12 (11°)

 Smith Center KS

Oct. 4
Oct. 13
Oct. 19

 Sep. 21, 1983

 Nov. 4, 1998

Oct. 16 (35°)
Oct. 19 (29°)
Nov. 12 (13°)

 Alton KS

Sep. 27
Oct. 3
Oct. 13

 Sep. 15, 1993

 Oct. 23, 2007

Oct. 7 (33°)
Oct. 13 (30°)
Oct. 21 (27°)

 Plainville KS

Oct. 7
Oct. 15
Oct. 25

Sep. 20, 1995

 Nov. 3, 1998

Oct. 16 (32°)
Oct. 16 (32°)
Nov. 6 (28°)

 Beloit KS

Oct. 6
Oct. 16
Oct. 25

 Sep. 22, 1995

 Nov. 10, 1998

Oct. 17 (34°)
Oct. 19 (31°)
Nov. 12 (14°)

 


Median Dates of First Fall Freeze and Hard Freeze (1981-2010)
(Midwestern Regional Climate Center)

(click images to enlarge)

Median Date of First 32-Degree Freeze Median Date of First 28-Degree Hard Freeze

 


 

South Central Nebraska and North Central Kansas 
30-Year Average First Frost/Freeze Dates (1983-2012)

(click images to enlarge)

Average 36-Degree Date (First Possible Frost)
Average 32-Degree Date (First Freeze)
Average 28-Degree Date (First Hard Freeze)

 


Nebraska First Fall Frost/Freeze Averages (maps courtesy NWS Omaha/Valley)
(click images to enlarge)

Average date of first 36-degree temps

Average date of first 32-degree temps

Average date of first 28-degree temps

 



 Average First Fall 32-Degree Dates for Kansas (courtesy the Kansas State Climatologist)

(click to enlarge)



A Look Back At The Unusually Early Frost/Freeze of September 1974:

One of the earliest freezes on record in parts of South Central Nebraska occurred the first week of September in 1974, as many locations dropped below the freezing mark on September 3rd. A surface weather map (see below, far left thumbnail image) from September 3, 1974 depicted just why such cold temperatures were observed. An unseasonably cold airmass roared into the region behind a strong cold front. Eventually, surface high pressure set up over the region, creating an ideal situation for a record early freeze. In fact, note the hand written comment "Record early damaging frosts, corn belt area" at the top of the weather map. Cooperative Observation forms for Gothenburg and Greeley, Nebraska are also shown below. The Gothenburg observer noted "Clear. Froze. Ice. Crop Damage" on the right side of the form on the 3rd. Finally, it is interesting to note both Gothenburg and Greeley recorded freezing temperatures again just ten days later on September 13, 1974.  

September 3, 1974 Weather Map

(click to enlarge)

Gothenburg, NE Observation Form
September 1974

(click to enlarge)

Greeley, NE Observation Form
September 1974

(click to enlarge)

 

This page was composed by the staff at the National Weather Service in Hastings, Nebraska.

 



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