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Adelphi, Maryland Weather

Cicadas claim the afternoon. Day 14 of summer. Read this microseason across nine climate regions →

Adelphi weather forecast — hour by hour, 7-day outlook, NOAA radar

Adelphi, MD
Saturday, July 4 at 7:11 PM
78
°
Overcast
Feels like
76°
Humidity
64%
Wind
18 mph
Sunrise
1:47 AM
Sunset
4:36 PM
Adelphi, MD
Hour by hour · 24h
24-Hour ForecastAdelphi, MD: 24-hour forecast. Temperatures range from 75 to 97 degrees Fahrenheit with a 42% chance of precipitation at 7 PM.
L 75°H 97°
Adelphi, MD
7-day forecast
  1. Today
    Jul 4
    Heavy Drizzle
    42%
    0.05″
    101°78°—
  2. Sunday
    Jul 5
    Heavy Rain
    52%
    0.62″
    97°75°-4°
  3. Monday
    Jul 6
    Light Drizzle
    81%
    —
    85°74°-12°
  4. Tuesday
    Jul 7
    Thunderstorm
    81%
    0.29″
    89°72°+4°
  5. Wednesday
    Jul 8
    Light Rain
    38%
    0.20″
    77°70°-12°
  6. Thursday
    Jul 9
    Overcast
    12%
    —
    93°68°+16°
  7. Friday
    Jul 10
    Drizzle
    42%
    0.06″
    92°73°-1°
Adelphi, MD
Next 24 hours · Mild now
HOT 90°70°88°105°6p12a6a12pnow 78°high 97°low 75°PRECIP %
Adelphi, MD
Anemometer · 24h winds · from true
NESW
From · True
N
353° · veering 87°
Direction
N
353°
Sustained
18
mph
Gust
28
mph
Peak 24h
28
avg 5
Beaufort · 4 · MOD BRZ
0
CALM
<1
1
LIGHT AIR
1–3
2
LIGHT BRZ
4–7
3
GENTLE BRZ
8–12
4
MOD BRZ
13–18
5
FRESH BRZ
19–24
6
STRONG BRZ
25–31
7
NEAR GALE
32–38
24h · sust vs gust · mph
avg 5 · pk 28 @ 7:00p
0102030MPHB1B2B3B4B5B6B7-21h-18h-15h-12h-9h-6h-3h-24hNOWpk 304SUSTGUST
−24h−18h−12h−6hnow
Sustained 18 mph with gusts pulsing to 28 — flags snap, branches bend.
Adelphi, MD
Barometer · 24h pressure · mb
STORMRAINCHANGEFAIRDRY9901000101010201030
Pressure · mb
1006.4
+0.7 mb in 3h · rising · 29.72 inHg
Now
1006.4
mb
3h
+0.7
mb
12h
-1.8
mb
24h
-0.9
mb
Regime · RAIN
STORM
RAIN
CHANGE
FAIR
DRY
24h · Pressure · mb
range 1004–1009
1000STORM|RAIN10051010RAIN|CHG1015CHG|FAIR-21h-18h-15h-12h-9h-6h-3h-24hNOW1008.81004.11006.4
−24h−18h−12h−6hnow
Damp, unsettled regime — wet weather lingers nearby.
Adelphi, MD
Air quality
112
AQI
Unhealthy for Sensitive Groups
↑+59 in 6h

AQI 112 (Unhealthy for Sensitive Groups), driven by Ozone. AQI up 59 in the last 6 hours — air quality is degrading. Ozone at AQI 70. Overcast through the UV peak window (cloud cover ~100%) — afternoon ozone should stay flat.

CAUTION Sensitive groups (children, elderly, respiratory conditions) should limit prolonged outdoor exertion.

PM 2.5Good
10.0μg/m³
PM 10Good
11μg/m³
NO₂Good
9μg/m³
OzoneDRIVERUnhealthy SG
119μg/m³
UV IndexLow
0.4

What's driving it

Ozone × UV × Sky

Ozone at AQI 70. Overcast through the UV peak window (cloud cover ~100%) — afternoon ozone should stay flat.

Present
AQI 70
UV peak
0.3 at 1 PM
Sky at peak
overcast
Projected peak
AQI 8

PM × Wind × Precip

PM2.5 at 10.0 µg/m³, PM10 at 10.5 µg/m³ — typical background levels with no transport signature.

PM2.5/PM10
0.95
Wind
breezy
Recent rain
1h in last 6h
Pattern
background

Trends

Seven days of AQI and PM2.5.

Hourly air-quality data from the Copernicus Atmosphere Monitoring Service, charted across the past and next several days. Dashed lines mark the AQI breakpoints at 50 (Good → Moderate) and 100 (Moderate → Unhealthy for Sensitive Groups).

7-DAY AQI TREND50100SATSUNMONTUEWEDTHUFRISAT7-DAY PM2.5 TREND · μg/m³350
Adelphi, MD
Sky cover · visibility · 24h
Cloud cover
100%
OVERCAST
100%0%−24h−18h−12h−6hnow
Visibility
57.1mi
UNLIMITED
115 mi0 mi−24h−18h−12h−6hnow
Earth · GOES-19 ABI
Full Disk · Visible · GeoColor
GOES-19 full disk Visible · GeoColor
True-color daytime, blue/IR sandwich at night
23:11 UTC · Adelphi, MD · NOAA NESDIS / STAR · up to 10848 px
Continental US · GOES-19 ABI
CONUS Sector · Visible · GeoColor
GOES-19 CONUS Visible · GeoColor
Daytime true-color, blue-light/IR sandwich at night
23:11 UTC · Adelphi, MD · NOAA NESDIS / STAR · 5-min cadence · up to 10000 px
Adelphi, MD
Satellite · infrared · animated
Adelphi, MD
Loading IR frames…
IR · cloud-top temp© RainViewer · Carto
Adelphi, MD
Almanac · Saturday, July 4
If the first of July be rainy weather, 'twill rain more or less for four weeks together.
Civil dawn
5:16 AM
Sunrise
1:47 AM
Daylight
14h 49m
Sunset
4:36 PM
Civil dusk
9:10 PM
Planting note
Harvest early potatoes. Begin drying onions on the surface.
Adelphi, MD
The moon
Waning Gibbous
78% illuminated
Moonrise
10:59 PM
Moonset
10:12 AM
In sign
♓︎ Pisces
Adelphi, MD
Microseason
Jul 1–5

Cicadas claim the afternoon

plant
Jan 151% of the yearDec 31

Read this microseason across nine climate regions →

Adelphi at a glance

  • Today vs. normal: 5°F above the seasonal normal for this latitude
  • Last frost: April 10 (climatological average for this latitude)
  • Microseason: Jul 1–5
  • Planting window: Harvest early potatoes. Begin drying onions on the surface.

16-Day Forecast — Adelphi

  1. Sat101°78°42%
  2. Sun97°75°52%
  3. Mon85°74°81%
  4. Tue89°72°81%
  5. Wed77°70°38%
  6. Thu93°68°12%
  7. Fri92°73°42%
  8. Sat92°70°37%
  9. Sun82°71°22%
  10. Mon82°70°20%
  11. Tue88°66°17%
  12. Wed94°71°33%
  13. Thu95°71°37%
  14. Fri91°76°42%
  15. Sat95°72°44%
  16. Sun90°71°46%

Forecast data from Open-Meteo (CC BY 4.0).

Right now in the garden

Peak growing season

As of July 4, the growing season is at its peak — frost is months away. Continue succession-planting beans and summer squash. Start fall brassicas (broccoli, cabbage, kale) from seed indoors for transplanting in late summer.

SPC Convective Outlook

Storm Prediction Center — Adelphi

SPC has placed Adelphi in the Enhanced Risk category for severe thunderstorms today.

  • TODAYENHEnhanced Risk
  • TOMORROWSLGTSlight Risk
  • DAY 3TSTMGeneral Thunderstorms

Numerous severe storms likely. Tornadoes, large hail, and damaging wind gusts possible across the area. Track NWS warnings if storms develop.

Source: NOAA / NWS Storm Prediction Center categorical convective outlook. Outlooks are re-issued multiple times per day; this page reflects the most recent SPC polygons covering the city’s coordinates.

January 1–5: The year turns in silence.January 6–10: Ice thickens on still water.January 11–15: Shortest shadows lengthen.January 16–20: Pheasants begin to call.January 21–25: Springs begin to thaw.January 26–31: Chickadees announce dawn.February 1–5: East wind softens the frost.February 6–10: Sap begins to rise.February 11–15: First snowdrops appear.February 16–20: Red-winged blackbirds return.February 21–25: Rain begins to replace snow.February 26–28: Skunk cabbage pushes through ice.March 1–5: Ice withdraws from the reservoir.March 6–10: Crocuses open to weak sun.March 11–15: Peepers call from the marsh.March 16–20: Woodcocks spiral at dusk.March 21–25: Equinox — light overtakes dark.March 26–31: Forsythia opens along the fences.April 1–5: Cherry blossoms drift like snow.April 6–10: Warblers appear in the understory.April 11–15: Magnolias bloom and fall in a day.April 16–20: Dogwoods float above the forest.April 21–25: Lilacs perfume the evening.April 26–30: Last frost releases the garden.May 1–5: Warblers flood the Ramble.May 6–10: Tulip poplars light their candles.May 11–15: Shad run up the rivers.May 16–20: Roses open along the stoops.May 21–25: Firefly scouts appear at dusk.May 26–31: Strawberries ripen in the sun.June 1–5: Fireflies rise from the lawn.June 6–10: Elderflowers open in hedgerows.June 11–15: Solstice approaches — longest light.June 16–20: Honeysuckle sweetens the night.June 21–25: Solstice — the sun stands still.June 26–30: Lightning bugs drift through oaks.July 1–5: Cicadas claim the afternoon.July 6–10: Queen Anne's lace lines the roads.July 11–15: Thunder builds each afternoon.July 16–20: Corn reaches for the tassels.July 21–25: Dog days settle in the haze.July 26–31: Katydids begin their chorus.August 1–5: Night falls a minute earlier.August 6–10: Sunflowers face the morning.August 11–15: Goldenrod begins to bloom.August 16–20: Crickets pulse through warm nights.August 21–25: First cool morning surprises.August 26–31: Monarchs stage for flight.September 1–5: School buses reappear.September 6–10: Asters purple the roadsides.September 11–15: Hawk migration over the Hudson.September 16–20: Equinox — dark overtakes light.September 21–25: Apples hang heavy on the branch.September 26–30: Geese begin to chevron south.October 1–5: Witch hazel blooms as others fade.October 6–10: Maples begin to blaze.October 11–15: Frost paints the garden black.October 16–20: Oaks turn bronze and russet.October 21–25: Leaves rattle down the gutters.October 26–31: Clocks fall back — dusk at five.November 1–5: Ginkgos drop overnight.November 6–10: Last leaves cling stubbornly.November 11–15: Juncos arrive from the north.November 16–20: Bare branches reveal the sky.November 21–25: First flurries dust the rooftops.November 26–30: Woodsmoke curls through the block.December 1–5: Darkness settles before dinner.December 6–10: Holly and winterberry persist.December 11–15: Shortest day approaches.December 16–20: Ice begins to form at the edges.December 21–25: Solstice — the sun begins return.December 26–31: The year turns in silence.🌱February 14 — First skunk-cabbage spathes thaw their way up☀️March 20 — Spring equinox — day and night balance🌸April 5 — Cherry blossoms peak in the parks🐦May 10 — Warbler migration peaks along the coast✨May 25 — First fireflies scout the meadows at dusk🌞June 21 — Summer solstice — longest day🦗July 25 — Peak cicada chorus in the afternoons🌊August 18 — Warmest sea-surface temperatures of the year🍂September 22 — Autumn equinox — the slow turn❄️October 25 — First widespread frost in the suburbs🍁November 10 — Peak leaf color across the Hudson Valley🌙December 21 — Winter solstice — longest night

Microseason · July 1–5

Cicadas claim the afternoon

Annual cicada buzz begins, peaking in the heat of the day.

Day 185 of 365 · Wedge 37 of 72

The solar year drawn as a wheel of 72 five-day windows. Each wedge is one microseason; the four colored arcs mark winter, spring, summer, and autumn; the small icons sit at notable phenological events. The crimson pointer creeps clockwise as the year turns.

Planting calendar

MonthPlantHarvest
January——
February——
March——
Aprillettuce, peas, spinach, radishes—
Maylettuce, peas, spinach, radishes, tomatoes, peppers, beans, squashlettuce, peas, radishes
Junetomatoes, peppers, beans, squashlettuce, peas, radishes
Julytomatoes, peppers, beans, squashtomatoes, beans, summer squash
August—tomatoes, beans, summer squash
Septemberfall brassicas, garlic (overwinter), carrotstomatoes, beans, summer squash
Octoberfall brassicas, garlic (overwinter), carrotswinter squash, tomatoes (last)
November——
December——

A year in weather

Adelphi's warmest month is July (~78°F mean) and its coldest is January (~32°F). Rainfall peaks in August (4.2 inches) and bottoms out in October (2.6 inches).

MonthMean tempPrecipRainy days
January32°3.3″13
February35°2.8″12
March44°3.4″15
April55°3.7″17
May63°3.5″18
June72°3.9″17
July78°3.2″17
August77°4.2″18
September70°3.4″14
October59°2.6″11
November46°3.6″12
December37°3.9″14

Regional context

By the nearest station's NOAA NCEI 1991-2020 normals, Adelphi sees 32°F Januarys and 78°F Julys, a 46°F range, plus around 41.5 inches of precipitation across 175 days.

Adelphi's precipitation spreads evenly: August peaks at 4.2 inches on 17.8 wet days, while October holds 2.6 inches over 11.1 — no month dominates Adelphi's rain calendar. That lines Adelphi up with places like Langley Park, MD, Hillandale, MD and College Park, MD, fed by overlapping storm tracks.

Adelphi's growing window opens around mid-April, once Adelphi's overnight lows stop freezing — sow peas, lettuce, spinach, and radishes. Warm-soil crops in Adelphi wait about two weeks past Adelphi's last frost, once the soil warms. Adelphi's window closes around mid-November as overnight lows return below freezing. Within Adelphi, cold-air pooling chills low spots by 5-10°F, shifting Adelphi's local frost dates.

Similar climates: Langley Park, MD, Hillandale, MD, College Park, MD, University Park, MD, Takoma Park, MD.

Frequently asked

When does it freeze in Adelphi?
Frost typically leaves Adelphi by mid-April and returns to Adelphi near mid-November.
What is the rainy season in Adelphi?
Rainfall in Adelphi peaks in August near 4.2 inches, out of about 42 inches annually.
What is the warmest month in Adelphi?
The warmest stretch in Adelphi comes in July, around 78°F on average.
What is the coldest month in Adelphi?
On average January is the chilliest month in Adelphi, about 32°F.
When can I start a vegetable garden in Adelphi?
Time tomatoes in Adelphi for two weeks after mid-April; peas and greens start at Adelphi's frost line.
How many rainy days does Adelphi get?
Adelphi averages about 175 days with measurable rain or snow each year.
What hardiness zone is Adelphi?
Adelphi's USDA zone comes from its January mean (32°F); enter the ZIP on the USDA lookup for the number.
What is the 10-day forecast for Adelphi?
Adelphi's extended outlook — daily high and low temperatures and precipitation chances for each upcoming day — is in the daily forecast above.
Will it rain this week in Adelphi?
See this week's day-by-day rain chances for Adelphi in the daily forecast above, and the next 24 hours in the hourly chart.
What is the weather like right now in Adelphi?
Current conditions for Adelphi and the next 24 hours — temperature, precipitation chance, and wind by the hour — are in the hourly forecast chart above.
How often is the Adelphi forecast updated?
The Adelphi forecast on this page is built from Open-Meteo weather-model data and refreshes regularly through the day.
When are sunrise and sunset in Adelphi?
Today's sunrise and sunset times for Adelphi are in the Almanac section above, along with civil dawn, civil dusk, and day length. Day length is longest near the summer solstice and shortest near the winter solstice.
How accurate is the weather forecast for Adelphi?
The next few days in Adelphi's forecast are the most reliable; accuracy declines beyond about a week as weather-model uncertainty grows.

Climate

Adelphi's warm-summer humid continental climate in Maryland pairs 32°F Januarys with 78°F Julys, 46°F apart across the seasons.

Across the year, Adelphi collects about 42 inches of precipitation over roughly 175 days with measurable rain or snow.

The 46°F gap between Adelphi's summer and winter, at 39.0°N, shapes Adelphi's frost calendar.

All cities in Maryland →

Washington, DC weather →

ZIP codes in Adelphi

  • 20783
  • 20787

Climate normals from the Open-Meteo Climate API. Köppen approximation from NOAA NCEI U.S. Climate Regions. See methodology for data sources, editorial rules, and corrections. Maintainer: Brian Tighe.