Data Date: June

June 2023 – Cool with Variable Precipitation Across Delaware

Posted on | by Dan Leathers

June Temperatures

Preliminary data indicates that the statewide average temperature in June was 70.6° F, which is 2.0° F below the 1991-2020 mean value of 72.6° F (Figure 1).  June 2023 was the second month in a row with below normal temperatures. 

June Precipitation

Delaware’s statewide precipitation for June 2023 averaged 3.31 inches, 0.78 inches below the 1991-2020 mean of 4.09 inches (Figure 2).  This month’s statewide precipitation value fell within the “normal” range since observations began in 1895.

Statewide Spatial Anomalies

Data from the Delaware Environmental Observing System (DEOS) show that temperature departures were uniformly negative across the entire state (Figure 3) with many locations seeing negative anomalies of more than 3° F.  This month’s precipitation was extremely variable across the State with values ranging from approximately 2 inches in Sussex County to nearly 12 inches at Prices Corner in Wilmington (Figure 4). This large variability was due to the convective nature of the month’s precipitation with several intense thunderstorms impacting isolated areas.   

National Anomalies

Temperatures were generally below normal across the eastern and southwestern United States (Figure 5), while much of the northern tier and Texas saw above normal temperatures (Figure 5).  Precipitation departures were varied across the country, with the central one-third of the country seeing mainly below normal values (Figure 6). The 500 hPa height pattern for June shows a weak jet stream trough covering most of the eastern United States, contributing to the temperature anomalies found across that region (Figure 7).

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June 2022 – Near Normal Temperature and Precipitation Across Delaware

Posted on | by Dan Leathers

June Temperatures

Preliminary data indicates that the statewide average temperature in June was 72.2o F, which is 0.4o F below the 1991-2020 mean value of 72.6o F (Figure 1).  Although June was slightly cooler than normal compared to the 1991-2020 time period, June 2022 still ranked in the warmest one-third of all Junes since records began in 1895.

June Precipitation

Delaware’s statewide precipitation for June 2022 averaged 3.51 inches, 0.58 inches below the 1991-2020 mean of 4.09 inches (Figure 2).  This month’s precipitation total was in the “normal” category based upon records dating back to 1895.

Statewide Spatial Anomalies

Data from the Delaware Environmental Observing System (DEOS) show that temperature departures were uniformly negative across the State, with some stations as much as 2.5o F  below normal for the month (Figure 3).  Precipitation varied across Delaware, but most stations recorded below average rainfall for the month (Figure 4).  Kent County saw the largest negative precipitation anomalies of over 2.5 inches in some locations.  The positive precipitation departure at Seaford was the result of heavy convective rainfall that occurred with a frontal passage on June 27th.

National Anomalies

Temperatures were above normal across the central and southern tier of the United States, with many areas seeing positive departures of 5o – 7o F.  The northwest and northeast portions of the country saw near normal temperatures (Figure 5).  Precipitation anomalies varied greatly across the country (Figure 6), with dry conditions across the majority of the nation except for Arizona and New Mexico, and the Pacific Northwest.  The 500 hPa height pattern for June shows a jet stream ridge located over much of the United States (Figure 7) accounting for the positive temperature anomalies across much of the country (Figure 5).

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Bright blue sky and the Sun

June 2021 – Warm and Dry Across Delaware

Posted on | by Dan Leathers

June Temperatures

Preliminary data indicates that the statewide average temperature in June was 74.5° F, which is 2.4° F above the 1981-2010 mean value of 72.1° F (Figure 1).  The statewide temperature in June 2021 was the 5th warmest since observations began in 1895.

June Precipitation

Delaware’s statewide precipitation for June 2021 averaged 2.82 inches, 0.91 inches below the 1981-2010 mean (Figure 2).  This placed this month’s precipitation total in the bottom one-third of all years since 1895.

Statewide Spatial Anomalies

Data from the Delaware Environmental Observing System (DEOS) show that temperature departures were above normal except across far western portions of Kent and Sussex counties (Figure 3).  Precipitation was below normal at most stations throughout the State, however, there were localized areas of higher-than-normal precipitation associated with the convective (thunderstorm) nature of summer precipitation (Figure 4).

National Anomalies

Temperatures were generally below normal across much of the southeastern United States.  Warmer than normal temperatures were found across the remainder of the country (Figure 5).  Precipitation anomalies varied greatly across the country with dry conditions in much of California and the Northwest United States.  Pockets of very wet conditions were found across much of the southern tier of the country (Figure 6).  The 500 hPa height pattern for June shows a strong jet stream ridge located over the western United States (Figure 7), leading to the very warm and dry conditions across this region.

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Dry cracked tan ground

June 2020 – Warm and Dry Across Delaware

Posted on | by Dan Leathers

June Temperatures

Preliminary data indicates that the statewide average temperature in June was 74.1o F, which is 2.0o F above the 1981-2010 mean value of 72.1o F (Figure 1).  June 2020 was the 8th warmest since observations began in 1895.

June Precipitation

Delaware’s statewide precipitation for June 2020 averaged 2.21 inches, 1.52 inches below the 1981-2010 mean (Figure 2).  The June 2020 precipitation amount was the 17th driest since 1895, placing this month in the driest one-third of all Junes since the start of observations.

Statewide Spatial Anomalies

Data from the Delaware Environmental Observing System (DEOS) show that temperature departures were generally above normal throughout the State (Figure 3).  Precipitation was below normal at almost all locations except for a few stations where heavier convective storms occurred during the month (Figure 4).

National Anomalies

Temperatures were above normal across the Great Plains and much of the central portion of the country, while near normal temperatures were found in both the northwest and southeast regions of the United States (Figure 5).  Precipitation varied greatly across the country, with little to no precipitation falling across the desert southwest, and below normal precipitation dominating the northeast and central portions of the United States (Figure 6).  The 500 hPa height pattern for June showed a weak ridge dominating the central United States leading to generally warm and dry weather across that region (Figure 7).

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June 2019 – Warm and Wet Conditions Across Delaware

Posted on | by Dan Leathers

June Temperatures

Preliminary data indicates that the statewide average temperature in June was 73.8°F, which is 1.7°F above the 1981-2010 mean value of 72.1°F (Figure 1). This places June 2019 as the 10th warmest since records began in 1895.

June Precipitation

Delaware’s statewide precipitation for June 2019 averaged 4.87 inches, 1.14 inches above the 1981-2010 mean (Figure 2). Delaware’s June precipitation was in the top 0ne-third of values for the last 125 years.

Statewide Spatial Anomalies

Data from the Delaware Environmental Observing System (DEOS) show that temperature departures were above normal across much of the state (Figure 3), with most stations seeing only small positive or negative temperature anomalies. Precipitation departures were significantly above normal across the northern portions of the State, while several stations across southern Delaware saw precipitation values near normal (Figure 4).

National Anomalies

The United States saw both positive and negative temperature anomalies during June, with the Gulf Coast and Pacific Coast experiencing the highest positive anomalies (Figure 5). Cool conditions were the rule across much of the central U.S. and New England. Precipitation across the U.S. varied greatly, with much below normal precipitation falling across the western U.S. and above normal values found in the Ohio Valley Region (Figure 6). The 500 hPa height pattern for June showed weak anomalous troughing of the jet stream over the Central U.S. and New England, contributing to the cool conditions in these locations (Figure 7). No other strong jet stream anomalies were present over the continental U.S.

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Foam from gentle waves glides over sand

2018 Summer Season Warm with Near Normal Precipitation Across Delaware

Posted on | by Dan Leathers

 

 

Summer Temperatures

Preliminary data indicates that summer temperatures averaged 76.2°F during the summer season, 1.7°F above the 30-year “normal” of 74.5°F (Figure 1). Summer 2018 is tied with the summer of 2005 as the 6th warmest since records began in 1895.

Summer Precipitation

The statewide mean precipitation of 13.73 inches was 1.73 inches above the 1981-2010 normal of 12.0 inches. (Figure 2). This value placed the summer of 2018 in the “normal” range for precipitation since 1895.

Statewide Spatial Averages

Data from the Delaware Environmental Observing System (DEOS) show that summer temperature anomalies across the State were generally above normal, except for extreme western portions of Kent County (Figure 3). Summer precipitation totals varied greatly with location across the State (Figure 4). In general, stations in New Castle and Kent counties saw above normal precipitation during the summer season, while coastal areas of Sussex County saw significant precipitation deficits.

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Violet flowers contrasted against a golden sky

Delaware Experiences Near Normal Climatic Conditions During June 2018

Posted on | by Dan Leathers

 

 

 

June Temperatures

Preliminary data indicates that the statewide average temperature in June was 72.7°F, which is 0.6°F above the 1981-2010 mean value of 72.1°F (Figure 1). June 2018 was the 26th warmest June since 1895. While a large majority of the United States saw significantly above normal temperatures for June (Figure 2), Delaware’s temperatures were more consistent with temperature anomalies found across the mid-Atlantic and New England.

June Precipitation

Delaware’s statewide precipitation for June 2018 averaged 3.62 inches, 0.11 inches below the 1981-2010 mean (Figure 3). However, the year-to-date precipitation across Delaware continues to run above normal, with precipitation during the first six months of the year coming in as the 16th wettest since 1895, and the wettest since 2003, mainly as a result of heavy precipitation during February and May.

Statewide Spatial Averages

Data from the Delaware Environmental Observing System (DEOS)
show that temperature (Figure 4) departures were generally small and varied between positive and negative values across the State. This pattern of departures is expected for a month with near normal
temperature conditions. Precipitation departures also varied greatly from one location to another (Figure 5). This is due to the “convective nature” of the precipitation during the summer months, with most falling in thunderstorms that cover only a small area.

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Water drops collect on green plants

Warm and Wet Conditions Characterize the 2017 Summer Season Across Delaware

Posted on | by Dan Leathers

 
 

Summer Temperatures

Preliminary data indicates that summer 2017 ranked as the 15th warmest summer season since records began in 1895 (tied with the 1995 and 2008 summer seasons). The statewide mean summer temperature of 75.3°F was 0.8°F above the 1981-2010 mean value of 74.5°F (Figure 1).

Summer Precipitation

The statewide mean precipitation of 18.24 inches was 6.24 inches above the 1981-2010 normal of 12.0 inches, and was the 12th wettest summer season since 1895, and the 5th year in a row with above normal summer precipitation (Figure 2).

Statewide Spatial Averages

Data from the Delaware Environmental Observing System (DEOS) show that summer temperature anomalies varied between positive and negative, depending upon location within Delaware and Chester County, PA (Figure 3). The Wilmington/New Castle County Airport recorded 16 days of temperatures greater than or equal to 90°F, very near the 1948 – 2017 normal of 17 days.

Summer precipitation was above normal across the entire State (Figure 4). However, the size of the positive anomalies varied greatly from one location to another. The variable pattern of precipitation is due to the small-scale nature of convective storms; dropping heavy precipitation in some areas, while leaving others relatively dry.

 

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Dry sand with curvy vertical lines in it

June 2017: Warm and Dry Conditions Return to Delaware

Posted on | by Dan Leathers

 
 

June Temperatures

Preliminary data indicates that the statewide average temperature in June was 73.7°F; this was 1.6°F above the 1981-2010 normal of 72.1°F (Figure 1). June 2017 was the 10th warmest June since statewide records began in 1895.

June Precipitation

Delaware’s statewide precipitation for June 2017 averaged 2.28 inches, 1.45 inches below the 1981-2010 mean of 3.73 inches (Figure 2). Seven of the last nine months have seen below normal precipitation values across Delaware.

Statewide Spatial Averages

Data from the Delaware Environmental Observing System (DEOS) shows that temperatures were generally above normal across the State, although some stations actually recorded below normal temperatures for the month (Figure 3). Precipitation was below the long-term mean at a majority of sites statewide, with the largest negative anomalies found in Kent and Sussex counties (Figure 4).

 

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Pink flowers

Very Warm Temperatures and Near Normal Precipitation Characterize the 2016 Summer Season Across Delaware

Posted on | by Dan Leathers

 

Summer Temperatures

Preliminary data indicates that summer 2016 ranked as the 4th warmest summer season since records began in 1895. The statewide mean summer temperature of 76.6°F was 2.1°F above the 1981-2010 mean value of 74.5°F (Figure 1). Delaware’s four warmest summer seasons have all occurred since 2010.

Summer Precipitation

The statewide mean precipitation of 12.4 inches was 0.40 inches above the 1981-2010 normal of 12.0 inches, and was the 4th year in a row with above normal summer precipitation (Figure 2).

Statewide Spatial Averages

Data from the Delaware Environmental Observing System (DEOS) show that summer temperatures were above normal across the majority of the State, with northern New Castle County and Chester County, PA having the largest positive anomalies (Figure 3). The Wilmington/New Castle County Airport recorded 34 days of temperatures greater than or equal to 90°F, twice the normal number. Only two years, 2010 and 1988, had more 90°F summer days than 2016.

Summer precipitation varied significantly across the State depending upon location (Figure 4). The variable pattern of precipitation is due to the small-scale nature of convective storms; dropping heavy precipitation in some areas, while leaving others relatively dry.

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