Data Date: October

wet pond under very dry conditions

October 2025 – Near Normal Temperatures with Below Normal Precipitation Across Delaware

Posted on | by Dan Leathers

October Temperatures

Preliminary data indicates that the statewide average temperature in October was 57.9o F, which is 0.1o F below the 1991-2020 mean value of 58.0o F (Figure 1).  Although it was near normal for the last 30-year period (1991-2020), October 2025 still ranked in the top one-third of temperatures since observations began across Delaware in 1895. 

October Precipitation

Delaware’s statewide precipitation for October 2025 averaged 2.56 inches, 1.38 inches below the 1991-2020 mean of 3.94 inches (Figure 2).  October 2025 was tied with 1987 as the 48th driest October since records began in 1895.

Statewide Spatial Anomalies

Data from the Delaware Environmental Observing System (DEOS) show that temperature departures were mixed across the State (Figure 3), with many stations seeing negative anomalies in Kent and Sussex Counties, while much of New Castle County saw positive temperature departures.  Precipitation was below normal across almost the entire State (Figure 4) with most stations recording negative anomalies of between 0.5 and 1.5 inches.

National Anomalies

Temperatures were above normal across most of the central United States, while most of the Pacific Coast and much of the southeast Atlantic Coast saw slightly below or near normal temperatures (Figure 5).  Precipitation varied greatly across the country (Figure 6) with much of the eastern portions of the United States seeing negative precipitation anomalies except for portions of New England south through the Ohio Valley.  Most of the western United States recorded near or above normal precipitation for the month. The 500 hPa height pattern for October showed a weak jet stream ridge across the central portion of the country, contributing to the generally positive temperature anomalies across that region (Figure 7).

Global Anomalies

October 2025 ranked as the third warmest October on record for the globe since 1850.  Global temperatures were 2.21o F (1.23o C) above the 1901-2000 mean.  Particular warmth was found across central North America, and parts of Antarctica and the Arctic (Figure 8).

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October 2024 – Record Dry Conditions with Near Normal Temperatures

Posted on | by Dan Leathers

October Temperatures
Preliminary data indicates that the statewide average temperature in October was 59.0°F, which is 1.0o F above the 1991-2020 mean value of 58.0°F (Figure 1). October’s temperature was the 28th warmest since records began in 1895.

October Precipitation
Delaware’s statewide precipitation for October 2024 averaged 0.03 inches, 3.91 inches below the 1991-2020 mean of 3.94 inches (Figure 2). October 2024 was not only the driest October since observations began in 1895, but the driest month ever observed across Delaware. In addition, the two-month period (September and October) was the driest two-month period ever observed across the state!

Statewide Spatial Anomalies
Data from the Delaware Environmental Observing System (DEOS) show that temperature departures varied between small positive and negative values depending upon the exact location across the State (Figure 3). Precipitation anomalies were uniformly negative across the entire state, with most departures ranging between 3 and 4 inches below normal for the month (Figure 4).

National Anomalies
Temperatures were near or above normal across the entire United States in October (Figure 5). Some locations in the southwest portion of the country saw anomalies of up to 9°F. Precipitation was below normal across most of the country (Figure 6). Much of the eastern one-half of the United States saw precipitation deficits of between 2 and 4 inches. The 500 hPa height pattern for October showed an anomalous jet stream ridge across the entire United States (Figure 7) contributing to the temperature anomalies across the country.

Global Anomalies
October 2024 ranked as the second warmest October on record for the globe since 1850. Global temperatures were 1.32°C (2.38°F) above the 1901-2000 mean. Particular warmth was found across the United States and the Arctic (Figure 8).

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October 2023 – Warm and Dry Across Delaware

Posted on | by Dan Leathers

October Temperatures
Preliminary data indicates that the statewide average temperature in October was 60.4°F, which was 2.4°F above the 1991-2020 mean value of 58.0°F (Figure 1).  This October’s temperature was the 13th warmest since observations began in 1895.

October Precipitation
Delaware’s statewide precipitation for October 2023 averaged 1.40 inches, 2.54 inches below the 1991-2020 mean of 3.94 inches (Figure 2).  This month’s statewide precipitation total was the 15th driest October total since observations began in 1895.

Statewide Spatial Anomalies
Data from the Delaware Environmental Observing System (DEOS) show that temperature departures were primarily positive across the state, with the highest positive departures found across the Wilmington metropolitan area (Figure 3).  Precipitation was below normal at every station, with some locations seeing negative anomalies of greater than three inches (Figure 4).

National Anomalies
Temperatures were generally above or near normal across the entire country, with the largest positive anomalies of 5° to 7°F found across New England (Figure 5).  Negative precipitation departures dominated the eastern and western United States, while the central portion of the country saw generally above normal precipitation (Figure 6). The 500 hPa height pattern for October shows a weak jet stream trough covering the Atlantic Coast of the U.S. (Figure 7).

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October 2022 – Below Normal Temperatures and Near Normal Precipitation Across Delaware

Posted on | by Dan Leathers

October Temperatures

Preliminary data indicates that the statewide average temperature in October was 56.1° F, which is 1.9° F below the 1991-2020 mean value of 58.0° F (Figure 1).  October 2022 was the coolest we have experienced since October 2003 and was 7.0° F cooler than last October.  

October Precipitation

Delaware’s statewide precipitation for October 2022 averaged 4.16 inches, 0.22 inches above the 1991-2020 mean (Figure 2).  This month’s precipitation value placed it the top one-third compared to October values since 1895.

Statewide Spatial Anomalies

Data from the Delaware Environmental Observing System (DEOS) show that temperature departures were uniformly negative across the state (Figure 3) with some stations seeing negative anomalies topping 3.0° F.  Precipitation observations were above normal in all areas except southwestern Sussex County.  Slaughter Beach, DE recorded precipitation 6.6 inches above normal for the month (Figure 4).  

National Anomalies

Temperatures were above normal across most of the northwestern United States, with the largest positive anomalies found in Washington and Oregon.  Only the Appalachians and parts of the southeast U.S. saw temperatures below normal.  In general, dry conditions prevailed across much of the eastern half of the United States, except for the coastal Mid-Atlantic, and parts of New England.  The Pacific Coast of the country also saw below normal precipitation values.  The 500 hPa height pattern for October shows a jet stream trough over the eastern United States and a ridge over the northwest portion of the country contributing to the temperature anomalies across those regions  (Figure 7).

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October 2021 – Very Warm with Near Normal Precipitation Across Delaware

Posted on | by Dan Leathers

October Temperatures

Preliminary data indicates that the statewide average temperature in October was 63.9o F, which is 6.8o F above the 1981-2010 mean value of 57.1o F (Figure 1).  October’s average temperature was the second highest recorded since observations began in 1895.  Only October 2007 has seen a higher mean temperature.

October Precipitation

Delaware’s statewide precipitation for October 2021 averaged 3.65 inches, 0.19 inches above the 1981-2010 mean (Figure 2).  This placed this month’s precipitation total in the normal range of all years since 1895.

Statewide Spatial Anomalies

Data from the Delaware Environmental Observing System (DEOS) show that temperature departures were far above normal across the entire State, with many stations seeing positive temperature anomalies of greater than 6o F (Figure 3).  Precipitation anomalies varied across the State with mostly positive precipitation anomalies found across Kent and New Castle Counties, and mixed anomalies across Sussex County (Figure 4).

National Anomalies

Temperatures were much above normal across the eastern two-thirds of the United States, with the largest positive temperature anomalies found across the Great Lakes and Northeast regions.  Much of the Pacific Coast and the Southwest experienced below normal temperatures during the month (Figure 5).  Precipitation anomalies varied greatly across the country (Figure 6), with excessively heavy precipitation falling in northern California.  The 500 hPa height pattern for October shows a very strong jet stream ridge located over eastern North America contributing to the extreme warmth across that region (Figure 7).

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Wet rain on fresh grass

October 2020 – Warm and Wet Across Delaware

Posted on | by Dan Leathers

October Temperatures

Preliminary data indicates that the statewide average temperature in October was 60.8o F, which is 3.7o F above the 1981-2010 mean value of 57.1o F (Figure 1).  October 2020 was tied with 1990 as the 9th warmest October since observations began in 1895.

October Precipitation

Delaware’s statewide precipitation for October 2020 averaged 5.16 inches, 1.70 inches above the 1981-2010 mean (Figure 2), placing this month’s precipitation total in the top one-third of all months since 1895. 

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 Sussex County (Figure 3).  Precipitation was above normal throughout the State, with departures of greater than four inches across much of southern Delaware (Figure 4). 

National Anomalies

Temperatures were above normal across the western and eastern portions of the United States (3 – 7o F), while below normal temperatures were found across the Great Plains, especially from Montana east through Minnesota (Figure 5).  Precipitation was far below normal across the southwestern portions of the country, with above normal precipitation covering much of the eastern one-third of the United States (Figure 6).  The 500 hPa height pattern for October exhibits a strong trough across the north-central portions of the country and ridging along both the Atlantic and Pacific coasts (Figure 7).

 

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October 2019 – Warm and Moist Across Delaware

Posted on | by Dan Leathers

October Temperatures

Preliminary data indicates that the statewide average temperature in October was 61.3°F, which is 4.2°F above the 1981-2010 mean value of 57.1°F (Figure 1). This places October 2019 as the 8th warmest since records began in 1895.

October Precipitation

Delaware’s statewide precipitation for October 2019 averaged 4.38 inches, 0.92 inches above the 1981-2010 mean (Figure 2). This placed the October 2019 precipitation amount in the top one-third of months since 1895.

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 the largest positive anomalies found across northern New Castle County. Precipitation was above normal at all stations across New Castle and Kent Counties (Figure 4), with several stations in Sussex County recording near or just below normal precipitation for the month.

National Anomalies

Temperatures were above normal throughout the eastern portion of the U.S, where some positive anomalies reached greater than 5°F (Figure 5). The western two-thirds of the U.S. saw below normal temperatures for the month, with some parts of the Rocky Mountains recording temperatures more than 10°F below normal. In general, precipitation was below normal across the western U.S. and above normal across the east (Figure 6). The 500 hPa height pattern for October showed a strong trough dominating the western U.S. (Figure 7), bringing the cold temperatures to that region.

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Rain drops on an autumn leaf

October 2018: Warm and Wet Conditions Persist Across Delaware

Posted on | by Dan Leathers

 

 

 

October Temperatures

Preliminary data indicates that the statewide average temperature in October was 60.3°F, which is 3.2°F above the 1981-2010 mean value of 57.1°F (Figure 1). October 2018 tied October of 2016 as the 11th warmest on record since 1895. Our warm October followed record setting warmth during September. The mid-Atlantic and Southeastern United States shared in this warmth with many areas seeing temperatures 3° – 5°F above normal (Figure 2).

October Precipitation

Delaware’s statewide precipitation for October 2018 averaged 4.95 inches, 1.49 inches above the 1981-2010 mean (Figure 3). This continued a string of four months with above normal precipitation across the First State.

Statewide Spatial Averages

Data from the Delaware Environmental Observing System (DEOS) show that temperature (Figure 4) departures were positive throughout the State, with the largest departures across Sussex County. Precipitation departures were positive across the southern two-thirds of the State, while many locations in New Castle County actually saw below normal precipitation (Figure 5).

 
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Autumn leaves shine in the bright Sun

Warm and Dry Conditions Characterize the 2017 Autumn Season Across Delaware

Posted on | by Dan Leathers
 

Autumn Temperatures

Preliminary data indicates that autumn 2017 ranked as the 3rd warmest autumn season since records began in 1895 (tied with three other autumn seasons). The statewide mean autumn temperature of 60.2°F was 2.6°F above the 1981-2010 mean value of 57.6°F (Figure 1).

Autumn Precipitation

The statewide mean precipitation of 8.23 inches was 2.60 inches below the 1981-2010 normal of 10.83 inches, and was in the driest one-third of autumns since 1895 (Figure 2). Precipitation during the autumn of 2017 was the lowest since the 2013 season.

Statewide Spatial Averages

Data from the Delaware Environmental Observing System (DEOS) show that autumn temperature anomalies were generally positive across the State, with a few locations experiencing near normal temperatures for the season (Figure 3).

Autumn precipitation was much below normal across the entire State, with the exception of extreme southeastern Sussex County (Figure 4). However, the size of the negative anomalies varied greatly from one location to another. Several stations in northern New Castle County and Chester County, PA saw negative anomalies of between four and six inches during the autumn months.

 

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Autumn leaves illuminated by the Sun

October Climate Conditions – Very Warm with Near Normal Precipitation Across Delaware

Posted on | by Dan Leathers

 

 

October Temperatures

Preliminary data indicates that the statewide average temperature in October was 62.6°F, which was 5.5°F above the 1981-2010 normal of 57.1°F (Figure 1). October 2017 was the 2nd warmest October since 1895. Only October 2007 has been warmer.

October Precipitation

Delaware’s statewide precipitation for October 2017 averaged 3.69 inches, 0.23 inches above the 1981-2010 mean (Figure 2), placing it just above normal for the month.

Statewide Spatial Averages

Data from the Delaware Environmental Observing System (DEOS) show that temperatures were above normal across the entire State with the largest positive temperature departures found across Chester County, PA and northern New Castle County, DE. (Figure 3). Precipitation departures varied according to location across the region (Figure 4), with no departures greater than two inches.

 

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