Data Date: January

January 2022 – Cold and Moist Conditions Across Delaware

Posted on | by Dan Leathers

January Temperatures

Preliminary data indicates that the statewide average temperature in January was 32.2° F, which is 3.0° F below the 1991-2020 mean value of 35.2° F (Figure 1).  Although below normal, January’s average temperature was in the middle 33% of all years since observations began in 1895.  

January Precipitation

Delaware’s statewide precipitation for January 2022 averaged 4.53 inches, 1.18 inches above the 1991-2020 mean (Figure 2).  This placed this month’s precipitation as the 23rd highest  January precipitation total since records began in 1895.

Statewide Spatial Anomalies

Data from the Delaware Environmental Observing System (DEOS) show that temperature departures were uniformly below normal across the entire State, with many stations seeing negative temperature anomalies of greater than 3° F (Figure 3).  Snowfall events on January 3rd and January 29th left significant snow accumulations, especially across central and southern Delaware, contributing to the higher than normal monthly precipitation.

National Anomalies

Temperatures were below normal across the eastern two-thirds of the United States, with the largest negative temperature anomalies found across the northern tier.  The western one-third of the country saw positive anomalies except in portions of the Pacific Northwest (Figure 4).  Precipitation anomalies varied greatly across the country (Figure 5), with excessively dry conditions across California, Nevada and much of the Great Plains.  Wet conditions were found across the Ohio Valley and the Mid-Atlantic regions.  The 500 hPa height pattern for January shows a strong jet stream trough located over eastern North America and a strong jet stream ridge over the western United States contributing to the temperature extremes across those regions (Figure 6).

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Snow-covered autumn leaves

January 2021 – Warm and Dry Across Delaware

Posted on | by Dan Leathers

January Temperatures

Preliminary data indicates that the statewide average temperature in January was 37.1° F, which is 3.0° F above the 1981-2010 mean value of 34.1° F (Figure 1).  January 2021 was the 28th warmest since observations began in 1895, placing it in the top one-third of all Januarys.

January Precipitation

Delaware’s statewide precipitation for January 2021 averaged 2.33 inches, 0.99 inches below the 1981-2010 mean (Figure 2).  This placed this month’s precipitation total as the 25th lowest of all Januarys since 1895, tied with January 1969.  Snowfall totaled 2.5 inches for the month at the Wilmington/New Castle County Airport, and this fell on the last day of the month.  Normal snowfall for January is 5.9 inches. 

Statewide Spatial Anomalies

Data from the Delaware Environmental Observing System (DEOS) show that temperature departures were positive at all stations, with the largest anomalies found across New Castle County (Figure 3).  Precipitation was generally below normal throughout the State.  

National Anomalies

Temperatures were above normal across the majority of the United States, with the largest temperature anomalies (10° F – 13° F) found across the north-central portion of the country (Figure 4).  Only the southwest United States saw below normal January temperatures.  Precipitation anomalies varied greatly across the country with particularly heavy precipitation across the central United States, while the northern tier of the country and Florida saw very dry conditions (Figure 5).  The 500 hPa height pattern for January shows a very strong jet stream ridge across northeastern North America resulting in the warm conditions across the northern portions of the country (Figure 6). 

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Bethany Beach with a colorful sky

January 2020 – Very Warm With Near Normal Precipitation

Posted on | by Dan Leathers

January Temperatures

Preliminary data indicates that the statewide average temperature in January was 40.1°F, which is 6.0°F above the 1981-2010 mean value of 34.1°F (Figure 1). January 2020 was tied with January of 2007 as the 11th warmest since 1895 in Delaware.

January Precipitation

Delaware’s statewide precipitation for January 2020 averaged 3.20 inches, 0.12 inches below the 1981-2010 mean (Figure 2). This placed the January 2020 precipitation amount in the “normal” category for the month.

Statewide Spatial Anomalies

Data from the Delaware Environmental Observing System (DEOS) show that temperature departures were uniformly above normal throughout the State (Figure 3), with some stations more than 6°F above the 30-year mean. Precipitation was below normal across Kent and Sussex Counties, while several stations in New Castle County had small positive precipitation departures (Figure 4).

National Anomalies

Temperatures were above normal across the majority of the U.S, with some departures reaching 7° to 10°F in the Northeast (Figure 5). Precipitation varied greatly across the U.S. with very wet conditions across the central States while the extreme southwest remained very dry (Figure 6). The 500 hPa height pattern for January showed a ridge dominating the eastern half of the country (Figure 7), bringing the warm conditions to our region.

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Snow flake up close

January 2019 – Temperature and Precipitation Near Normal Across Delaware

Posted on | by Dan Leathers

 

 

January Temperatures

Preliminary data indicates that the statewide average temperature in January was 34.6°F, which is 0.5°F above the 1981-2010 mean value of 34.1°F (Figure 1). Delaware’s January temperatures were considered “normal” for the month in comparison to all data going back to 1895, not falling within the bottom or top one-third of January values in the last 125 years.

January Precipitation

Delaware’s statewide precipitation for January 2019 averaged 3.45 inches, 0.13 inches above the 1981-2010 mean (Figure 2). Snowfall was slightly below normal during the month in northern Delaware with 5.6 inches of snow recorded at the Wilmington – New Castle County Airport (normal is 6.6 inches). Moderately heavy snow fell in central and southern Delaware on the 13th with up to four inches recorded in much of Kent and Sussex counties.

Statewide Spatial Averages

Data from the Delaware Environmental Observing System (DEOS) show that temperature departures were near or below normal across the entire state (Figure 3). Precipitation departures varied greatly, but were uniformly small (Figure 4), with most stations seeing departures of 1 inch or less.

National Anomalies

Temperature anomalies across the U.S. were generally small, with much of the northwest experiencing above normal temperatures along with much of the southeast. The upper mid-west and Great Lakes regions experienced below normal temperatures during the month of January (Figure 5). Precipitation was generally above normal for much of the northeast quadrant of the country, while much of the northern tier of the U.S. was drier than normal (Figure 6).

 

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Branches frozen in the cold

Conditions Continue Cool and Dry Across Delaware in January 2018

Posted on | by Dan Leathers

 

 

January Temperatures

Preliminary data indicates that the statewide average temperature in January was 32.6°F, which is 1.5°F below the 1981-2010 mean value of 34.1°F (Figure 1). This was the third month in a row with
temperatures at or below normal across Delaware. Most of the United States east of the Rocky Mountains shared in Delaware’s colder than normal January temperatures (Figure 2).

January Precipitation

Delaware’s statewide precipitation for January 2018 averaged 2.97 inches, 0.35 inches below the 1981-2010 mean (Figure 3). Snowfall was also below normal during the month in northern Delaware with
only 3.5 inches of snow recorded at the Wilmington – New Castle County Airport . However, a storm on January 4th brought heavy snowfall to Sussex County, with many locations receiving more than
10 inches of snow.

Statewide Spatial Averages

Data from the Delaware Environmental Observing System (DEOS) show that temperature departures were uniformly below normal across the entire State (Figure 4). Precipitation departures were
below normal at all but a few scattered stations (Figure 5), with most stations seeing departures of 1 inch or less.

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Dry plant with muted tan colors

Very Warm and Dry Conditions Characterize the 2016-2017 Winter Season Across Delaware

Posted on | by Dan Leathers

 
 

Winter Temperatures

Preliminary data indicates that winter temperatures were far above the 30-year “normal” during the winter season. The statewide mean winter temperature of 40.8°F was 4.5°F above the 1981-2010 mean value of 36.3°F (Figure 1). This made winter 2016-2017 the 5th warmest since records began in 1895, and the second winter in a row in the top 5 warmest on record.

Winter Precipitation

The statewide mean precipitation of 7.19 inches was 2.57 inches below the 1981-2010 normal of 9.76 inches, and was the 17th driest winter season since records began in 1895 (Figure 2).

Statewide Spatial Averages

Data from the Delaware Environmental Observing System (DEOS) show that winter temperatures across the entire State were above normal, with the largest anomalies found in northern Sussex and northern New Castle counties in Delaware and in Chester County, PA (Figure 3).

Winter precipitation totals were significantly below normal across the entire State, with the driest conditions along the Sussex County coast (Figure 4). At the New Castle County Airport, only 5.6 inches of snow fell during the December through February winter season, a value far below the 1981-2010 mean of 17.7 inches. During March, another 3.4” of snow fell in northern Delaware bringing the total for the entire snow season (November through April) to 9.0 inches.

 

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Bird sitting on a branch

January 2017: Warm Temperatures and Near Normal Precipitation Across Delaware

Posted on | by Dan Leathers

 
 

January Temperatures

Preliminary data indicates that the statewide average temperature in January was 39.1°F; this was 5.0°F above the 1981-2010 normal of 34.1°F (Figure 1). January 2017 was the 14th warmest January since records began in 1895, and was 0.1°F warmer than December 2016. January 2017 was also the 8th month in a row with above normal temperatures across the First State.

January Precipitation

Delaware’s statewide precipitation for January 2017 averaged 3.21 inches, 0.11 inches below the 1981-2010 mean (Figure 2). A significant snowstorm blanketed the state on January 7th. This storm dropped over 10 inches of snow on some locations in Sussex County. Cold temperatures followed the storm with minimum temperatures dipping below zero in many snow-covered locations across Sussex County on the morning of January 9th (Figure 3).

Statewide Spatial Averages

Data from the Delaware Environmental Observing System (DEOS) shows that temperatures were above normal across the entire State, with departures reaching over 5.0°F in many locations (Figure 4). Total liquid precipitation was near, or just below normal across the entire State (Figure 5).

 

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Snowflake up close

January 2016: Temperature and Precipitation Near Normal Across Delaware

Posted on | by Dan Leathers

 

January Temperatures

Preliminary data indicates that the statewide average temperature in January was 34.2o F; this was 0.1°F above the 1981-2010 normal of 34.1°F (Figure 1). January 2016 was 16.7°F colder than December 2015, which was the warmest December ever recorded.

December Precipitation

Delaware’s statewide precipitation for January 2016 averaged 3.01 inches, 0.1 inches above the 1981-2010 mean (Figure 2). A major snowstorm impacted the State during January 22-24, with significant accumulations blanketing the entire State.

Statewide Spatial Averages

Data from the Delaware Environmental Observing System (DEOS) shows that temperatures were near normal across most of the State, with small departures at most stations (Figure 3). Total liquid precipitation was near, or just below normal across the entire State.

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Raindrops on glass

Very Warm and Moist Conditions Characterize the 2015-2016 Winter Season Across Delaware

Posted on | by Dan Leathers
 
 

 

Winter Temperatures

Preliminary data indicates that winter temperatures were far above the 30-year “normal” during the winter season. The statewide mean winter temperature of 41.1°F was 4.8°F above the 1981-2010 mean value of 36.3°F (Figure 1). This made winter 2015-2016 the 4th warmest since records began in 1895.

Witer Precipitation

The statewide mean precipitation of 11.47 inches was 1.71 inches above the 1981-2010 normal of 9.76 inches, and was the 3rd year in a row with above normal winter precipitation (Figure 2).

Statewide Spatial Averages

Data from the Delaware Environmental Observing System (DEOS) show that winter temperatures across the entire State were above normal, with the largest anomalies found in northern Sussex and northern New Castle counties in Delaware and in Chester County, PA (Figure 3).

Winter precipitation varied significantly across the State depending upon location. In general, the heaviest precipitation fell across interior Sussex County, DE (Figure 4). At the New Castle County Airport, 22.7 inches of snow fell during the December through February winter season, a value slightly above the 1981-2010 mean.

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Drops of water on bright green grass

Temperature and Precipitation Both Above Normal Across Delaware During 2015

Posted on | by Dan Leathers
 
 
 

Annual Temperatures

Statewide mean annual temperature in 2015 was 56.4°F according to preliminary data from the National Climatic Data Center (NCDC). This was 1.0°F above the 1981-2010 normal of 55.4°F (Figure 1) and was the 11th warmest year in Delaware since 1895.

Monthly temperatures varied greatly throughout the year (Figure 2). The first three months of 2015 saw much below normal temperatures, including the 6th coldest February since 1895. The last nine months of the year saw above normal temperatures, except for October, which was slightly below normal. Tremendous warmth ended the year with December temperatures averaging 12.4°F above the 1981-2010 mean. December 2015 was the warmest December on record, smashing the old record by 6.1°F.

Annual Precipitation

Statewide precipitation in 2015 averaged 46.37 inches, 2.04 inches above the 1981-2010 mean of 44.33 inches (Figure 3).

Monthly precipitation anomalies varied between positive and negative throughout the year, with seven months of below normal and five months of above normal precipitation (Figure 4). June saw the largest precipitation anomaly of 5.30 inches above the 30-year normal, helping to push the annual value above the long-term mean.

Statewide Spatial Averages

According to data from the Delaware Environmental Observing System (DEOS; deos.udel.edu), mean annual temperature anomalies varied across Delaware (Figure 5). Northern New Castle County, much of Sussex County, southern Kent County and Chester County, PA all experienced above normal temperatures for the year. Coastal Sussex County and western portions of News Castle and Kent counties saw below normal mean annual temperatures.

Precipitation across the region varied substantially in 2015, ranging from just under 40 inches to greater than 50 inches at several locations across the State (Figure 6).

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