Data Date: July

July 2023 – Warm with Above Normal Precipitation Across Delaware

Posted on | by Dan Leathers

July Temperatures

Preliminary data indicates that the statewide average temperature in July was 79.8o F, which is 2.4o F above the 1991-2020 mean value of 77.4o F (Figure 1).  July 2023 was tied with July 2019 as the 5th warmest since observations began in 1895.

 

July Precipitation

Delaware’s statewide precipitation for July 2023 averaged 6.75 inches, 2.33 inches above the 1991-2020 mean of 4.42 inches (Figure 2).  This month’s statewide precipitation total was the 13th wettest since observations began in 1895.

 

Statewide Spatial Anomalies

Data from the Delaware Environmental Observing System (DEOS) show that temperature departures were generally positive across the entire state (Figure 3).  This month’s precipitation, like last month, was extremely variable across the State with values ranging from less than 4 inches at Jones Crossroads to over 13 inches at Bridgeville (Figure 4), a distance of approximately 15 miles. As is often the case, this variability was a result of the convective nature of rainfall during the summer months.   

 

National Anomalies

Temperatures were generally above normal along the Atlantic and Pacific coasts and the southwest United States (Figure 5), while much of the northern plains saw below normal temperatures (Figure 5).  Precipitation departures were generally small across the entire country, except for portions of New England where significant above normal rainfall occurred (Figure 6). The 500 hPa height pattern for July shows a weak jet stream trough covering the upper Midwest and plains, contributing to the temperature anomalies found across that region and the precipitation anomalies in New England (Figure 7).

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July 2022 – Warm and Dry Conditions Continue Across Delaware

Posted on | by Dan Leathers

July Temperatures

Preliminary data indicates that the statewide average temperature in July was 79.0o F, which is 1.6o F above the 1991-2020 mean value of 77.4o F (Figure 1).  July 2022 was tied with July 1901 and 1999 as the 10th warmest since observations began in 1895. 

July Precipitation

Delaware’s statewide precipitation for July 2022 averaged 3.84 inches, 0.58 inches below the 1991-2020 mean (Figure 2).  This month’s precipitation ranking was in the “normal” range when compared to Julys since 1895.

Statewide Spatial Anomalies

Data from the Delaware Environmental Observing System (DEOS) show that temperature departures were above normal across the majority of the state (Figure 3).  Precipitation observations varied across the state due to the nature of the summer’s convective (thunderstorm) activity, with the largest negative precipitation anomalies occurring in coastal Sussex County (Figure 4).   

National Anomalies

Temperatures were above normal across most of the conterminous United States, with portions of Texas seeing positive departures of 5o – 7o F (Figure 5).  Precipitation anomalies varied greatly across the country (Figure 6), with very dry conditions across portions of California, Texas and from New Jersey through southern New England.  Wet conditions were found mainly across the Ohio River Basin.  The 500 hPa height pattern for July shows a weak jet stream ridge covering much of the United States (except the Northeast) contributing to the positive temperature anomalies across the country (Figure 7).

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July 2021 – Warm and Wet Across Delaware

Posted on | by Dan Leathers

July Temperatures

Preliminary data indicates that the statewide average temperature in July was 78.4o F, which is 1.8o F above the 1981-2010 mean value of 76.6o F (Figure 1).  The statewide temperature in July 2021 was tied as the 14th warmest since observations began in 1895.

July Precipitation

Delaware’s statewide precipitation for July 2021 averaged 5.75 inches, 1.61 inches above the 1981-2010 mean (Figure 2).  This placed this month’s precipitation total in the top 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 across the majority of the State (Figure 3).  Precipitation varied greatly across the State due to localized areas of convective (thunderstorm) activity during the month (Figure 4).

National Anomalies

Temperatures were generally below normal across much of the southeastern and southcentral United States, and New England.  Warmer than normal temperatures were found across the western one-third of the country, and across the mid-Atlantic region (Figure 5).  Some temperature anomalies were greater than 15o F for the month across the Pacific Northwest.  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 portions of Texas and New England (Figure 6).  The 500 hPa height pattern for July shows a strong jet stream ridge located over the western United States and Canada (Figure 7), leading to the very warm and dry conditions across this region.

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Rain droplets on grass blade

July 2020 – Record Warmth and Very Wet Across Delaware

Posted on | by Dan Leathers

July Temperatures

Preliminary data indicates that the statewide average temperature in July was 81.0o F, which is 4.4o F above the 1981-2010 mean value of 76.6o F (Figure 1).  July 2020 was the warmest July since observations began in 1895, and it is the warmest of any month on record since 1895 for Delaware.

July Precipitation

Delaware’s statewide precipitation for July 2020 averaged 6.42 inches, 2.28 inches above the 1981-2010 mean (Figure 2).  The July 2020 precipitation amount was the 17th wettest since 1895, placing this month in the wettest one-third of all Julys since the start of observations.

Statewide Spatial Anomalies

Data from the Delaware Environmental Observing System (DEOS) show that temperature departures were above normal throughout the State (Figure 3).  Precipitation was likewise above normal at nearly all locations (Figure 4).

National Anomalies

Temperatures were above normal across most of the eastern one-third of the country, while below normal temperatures were found in both the northwest United States and along the Pacific coast (Figure 5).  Precipitation varied greatly across the country as is common when convective rainfall dominates during the summer months (Figure 6).  The 500 hPa height pattern for July showed a ridge dominating the eastern portion of North America leading to generally warm weather across that region (Figure 7).

 

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July 2019 – Very Warm with Near Normal Precipitation Across Delaware

Posted on | by Dan Leathers

July Temperatures

Preliminary data indicates that the statewide average temperature in July was 79.4°F, which is 2.8°F above the 1981-2010 mean value of 76.6°F (Figure 1). This places July 2019 as the 6th warmest since records began in 1895.

July Precipitation

Delaware’s statewide precipitation for July 2019 averaged 3.79 inches, 0.35 inches below the 1981-2010 mean (Figure 2). Delaware’s July precipitation was in the middle 0ne-third of values for the last 125 years, putting it into the “normal” range for this month.

Statewide Spatial Anomalies

Data from the Delaware Environmental Observing System (DEOS) show that temperature departures were above normal throughout the State (Figure 3), with many stations seeing positive anomalies greater than 2.0°F. There was a mixture of positive and negative precipitation departures observed across the State (Figure 4). In general, northern New Castle County had greater than normal precipitation, while Kent and Sussex Counties saw below normal precipitation amounts during the month.

National Anomalies

The northeast quarter of the United States experienced above normal temperatures during July, with mixed temperature anomalies found throughout the rest of the country (Figure 5). Precipitation anomalies across the U.S. varied greatly, with above normal precipitation falling across the northern Great Plains, the southern Mississippi Valley and parts of the mid-Atlantic (Figure 6). In general, the southwest United States and California were dryer than normal. The 500 hPa height pattern for July showed weak anomalous ridging over the northeast portion of the Country (Figure 7), bringing the warm temperatures to that region.

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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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Voluminous clouds illuminated by sun

July 2018 was Warm and Wet Across Delaware

Posted on | by Dan Leathers

 

 

 

July Temperatures

Preliminary data indicates that the statewide average temperature in July was 77.3°F, which is 0.7°F above the 1981-2010 mean value of 76.6°F (Figure 1). July 2018 ranked in the top one-third for temperatures since 1895. During the month, 10 days at or above 90°F were recorded at the Wilmington/New Castle County Airport, approximately one more than average. Larger positive temperature anomalies were found across the rest of the northeast United States, and across most of the western and southwestern portions of the country (Figure 2).

July Precipitation

Delaware’s statewide precipitation for July 2018 averaged 5.68 inches, 1.54 inches above the 1981-2010 mean (Figure 3), placing this month in the wettest one-third of Julys since 1895. Although statewide totals for July were above normal, the month actually began very dry across most of the state, with approximately 80% of the month’s precipitation falling after July 20th.

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 during July. Precipitation departures also varied greatly from one location to another (Figure 5), but were generally positive contributing to the wet conditions statewide. Some locations saw precipitation anomalies more than four inches above normal.

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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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The Sun shining brightly upon grasses

July 2017: Warm and Very Wet Conditions Across the First State

Posted on | by Dan Leathers

 

 

 

July Temperatures

Preliminary data indicates that the statewide average temperature in July was 78.4°F; this was 1.8°F above the 1981-2010 normal of 76.6°F (Figure 1). July 2017 was the 12th warmest July since statewide records began in 1895.

July Precipitation

Delaware’s statewide precipitation for July 2017 averaged 8.47 inches, 4.33 inches above the 1981-2010 mean of 4.14 inches (Figure 2). This was the highest statewide precipitation total since September 2016, and the 6th wettest July since 1895.

Statewide Spatial Averages

Data from the Delaware Environmental Observing System (DEOS) shows that temperatures varied significantly across the state depending upon location (Figure 3). Precipitation was above the long-term mean at all sites statewide, with the largest positive anomalies found in northern New Castle and western 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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