Unusually Cold July Weather - A Record?

An unusually cold air-mass has settled in across the northern plains and promises to drop low temperatures into the 40s and 50s. For late July "normal" low temperatures range from close to 50 along the International Border to the low 60s in the heart of west central Minnesota Lakes country. Experiencing lows 5 to 10 degrees below a normal is not at all unusual. (For a slightly more detailed explanation of what normal means, click here)

What about record lows? A record low (or high) temperature is simply the lowest (or highest) for any given day, based on that stations period of record. For stations such as Fargo and UND/NWS, the period of record goes back over 110 years. Many stations in the Red River Valley and Lakes region have a shorter history; typically 60 years or less. The shorter the period of record, the greater the likelihood that major heat waves or cold snaps are not represented at that location. Another factor is location of equipment. Temperatures taken in town or airport locations can be quite a bit warmer than more rural locations. Equipment located in a river valley will have different - typically cooler - temperatures than one on a rise or the crest of a ridge.

Below is a list of record low temperatures at a variety of weather stations across the Red River Valley and Lakes Country. As you can see, having low temperatures in the 30s, while rare, has occurred in July. It is important to note the year of the verified, record low for July 27th as some stations have relatively short periods of record, or missing data that may bias the record low. Stations that are highlighted in yellow have a period of record that is less than 30 years, less than 30 years was used in the analysis or there are significant gaps in the data record.

Record Lows for July 27th from ACIS

State  Name  StationType  Record  Year
ND  MAYVILLE  COOP 31 1903
ND  PEMBINA  WBAN 39 1925
ND  LANGDON EXP FARM  COOP 41 1925
ND  DEVILS LAKE KDLR  WBAN 42 1925
ND  GRAND FORKS UNIV  COOP 42 1925
ND  PETERSBURG 2 N  COOP 42 1971
ND  EDMORE 1NW  COOP 43 1978
ND  MINNEWAUKAN  COOP 44 1902
ND  ENDERLIN 2W  COOP 45 1971
ND  GRAND FORKS INTL AP  WBAN 45 1971
ND  CAVALIER 7NW  COOP 46 1981
ND  FARGO HECTOR INTL AP  WBAN 46 1971
ND  HILLSBORO 3 N  COOP 46 1925
ND  FORMAN 5 SSE  COOP 47 1897
ND  MC LEOD 3 E  COOP 47 1915
ND  BALDHILL DAM  COOP 49 1948
ND  DEVILS LAKE MUNI AP  WBAN 52 2012
ND  LIDGERWOOD  COOP 52 2005
ND  SHEYENNE NORTH DAKOTA  RAWS 50 2005
ND  CASSELTON AGRONOMY FARM  COOP 47 1991
State  Name  StationType  Record  Year
MN  ITASCA UNIV OF MINN  COOP 36 1925
MN  WADENA 3 S  COOP 37 1904
MN  THORHULT  COOP 40 1971
MN  ARGYLE  COOP 41 1956
MN  CROOKSTON NW EXP STN  COOP 41 1925
MN  DETROIT LAKES 1 NNE  COOP 41 1981
MN  HALLOCK  COOP 41 1956
MN  RED LAKE FALLS  COOP 41 1925
MN  BAUDETTE  COOP 42 1971
MN  RED LAKE INDIAN AGCY  COOP 42 1971
MN  WARROAD  COOP 42 1918
MN  ADA  COOP 43 1925
MN  AGASSIZ REFUGE  COOP 43 1981
MN  ROTHSAY  COOP 43 1971
MN  THIEF RIVER FALLS 2N  COOP 43 1973
MN  MAHNOMEN 1 W  COOP 44 1971
MN  PARK RAPIDS MUNI AP  WBAN 44 1994
MN  FERGUS FALLS  COOP 45 1925
MN  TAMARAC WILDLIFE REF  COOP 45 1981
MN  MOORHEAD  COOP 46 1925
MN  OTTERTAIL  COOP 46 1973
MN  GEORGETOWN 1 E  COOP 47 1971
MN  ORWELL DAM  COOP 48 1994
MN  CROOKSTON  COOP 52 2012
MN  WARREN 7ESE  COOP 52 2012
MN  BRECKENRIDGE 3E  COOP 57 2012
MN  DETROIT LAKES 12E  COOP 60 2012
MN  GOODRIDGE 12 NNW  WBAN 42 2012
MN  ITASCA MINNESOTA  RAWS 46 2005
MN  ROSEAU MINNESOTA  RAWS 49 2008
MN  BADOURA MINNESOTA  RAWS 38 2005
MN  BEMIDJI MINNESOTA  RAWS 47 2005
MN  BAUDETTE MINNESOTA  RAWS 49 2005
MN  KELLIHER MINNESOTA  RAWS 45 2005
MN  AGASSIZ MINNESOTA  RAWS 44 2012
MN  DETROIT LAKES MINNESOTA  RAWS 46 2005
MN  CAMP NORRIS DNR  COOP 45 2012
MN  NEW YORK MILLS  COOP 45 2005
MN  BAUDETTE INTL AP  WBAN 45 2005
MN  BLACKDUCK  COOP 47 2004
Station Type: Abbreviation / Definition
COOP = Official NWS Cooperative Weather Station
RAWS = Remote Automated Weather Station
INTL / MUNI AP = International or Minicipal Airport
WBAN (archaic) = Weather Bureau Accounting Number, typically represents a longer term climate station

What is normal? What does that really mean? Without delving too deeply into the math behind the numbers, suffice it to say that the term normal as it is used in conjunction with a meteorological variable such as daily high or low temperature is somewhat misleading. The values that are presented as normal are derived by looking at the daily high and low temperature for a 30 year period then calculating the statistical average value. What is more telling is the range, or standard deviation, in the set of daily values. For instance, the "normal" low at the UND/NWS Grand Forks Climate Station for July 27th is 58 degrees. However, if we looked at the standard deviation for the morning low on July 27th we would see a range of low temperatures that would encompass the expected normal value. For the UND/NWS Climate Station that range is 52 to 64 degrees. In other words, having a morning low as cool as 52 or as warm as 64 on July 27th would truly be "normal" weather. Low temperatures colder - or warmer - would then represent a more unusual weather pattern.

The period of record (POR) means all the data ever taken at a particular station. However, the averages a.k.a. normals are usually formed using the most recent 30 year climatological record. This is a strictly defined 30 year period, in this case 1981-2010, updated once each decade. This 30 year period is assumed to accurately reflect the "climate" at the location. The next 30 year climate averages will be based on years 1991-2020, and will be prepared around 2022.

The Applied Climate Information System (ACIS) developed and maintained by the NOAA Regional Climate Centers (RCCs) is designed to manage the complex flow of information from climate data collectors to the end users of climate information. For more information click here.



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