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
|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||GRAND FORKS INTL AP||WBAN||45||1971|
|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||DEVILS LAKE MUNI AP||WBAN||52||2012|
|ND||SHEYENNE NORTH DAKOTA||RAWS||50||2005|
|ND||CASSELTON AGRONOMY FARM||COOP||47||1991|
|MN||ITASCA UNIV OF MINN||COOP||36||1925|
|MN||WADENA 3 S||COOP||37||1904|
|MN||CROOKSTON NW EXP STN||COOP||41||1925|
|MN||DETROIT LAKES 1 NNE||COOP||41||1981|
|MN||RED LAKE FALLS||COOP||41||1925|
|MN||RED LAKE INDIAN AGCY||COOP||42||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||TAMARAC WILDLIFE REF||COOP||45||1981|
|MN||GEORGETOWN 1 E||COOP||47||1971|
|MN||DETROIT LAKES 12E||COOP||60||2012|
|MN||GOODRIDGE 12 NNW||WBAN||42||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|
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.