Herndon weather in April

In April, Herndon sees average daytime highs of 66°F and overnight lows near 46°F, with 3.4 in of precipitation across 10.3 wet days and about 13 hours of daylight. It is the 7th-warmest and 6th-wettest month of the year here.

Highs climb over the month, from about 61°F in the first days to 69°F by the end. The sky is clear or mostly clear about 27% of the time in April, and the air most often feels dry.

Daylight stretches from about 12 h 24 min at the start of April to 13 h 36 min by month's end. Set against the rest of the year, April is Herndon's 9th-clearest and 4th-windiest month. For the whole year in context, see Herndon's year-round climate.

Daytime high
66°
7th warmest
Overnight low
46°
6th coldest
Precipitation
3.4 in
10.3 wet days
Daylight
13 hours
5:39 AM – 6:40 PM
Cloud cover
61%
9th clearest
Wind
7 mph
4th windiest
Solar energy
5.2 kWh/m²
Travel score
5.8
out of 10

Herndon is town in Virginia, United States.

Density
2,216/km²
people per km²
Founded
1858

Air quality: WHO Ambient Air Quality Database. Density & description: Wikidata (CC0), GeoNames.

Temperature in April

Average highAverage lowShaded bands: 10–90% of days

Highs climb over the month, from about 61°F in the first days to 69°F by the end.

A typical April day in Herndon reaches about 66°F in the afternoon and slips back to 46°F overnight — a 19°F spread between the day's warmth and the night's chill. On most days the high lands between 53°F and 79°F. Set against its neighbours, April runs about 12°F warmer than March and about 9°F cooler than May.

20°40°60°80°151015202530
Avg high (°F)Avg low (°F)
16041
26142
36142
46242
56243
66343
76344
86344
96444
106445
116445
126545
136546
146546
156646
166647
176647
186747
196747
206748
216748
226848
236849
246849
256949
266949
276950
286950
297050
307051

How April really feels in Herndon

Once humidity and wind are folded in, April averages 0 days that feel above 90°F and 0 that feel at or below 32°F — the comfort signal a plain temperature reading hides.

Days feeling ≥ 90°F
0
heat index over the day's high
Days feeling ≤ 32°F
0
wind chill below the day's low

April sits comfortably in between — no days that feel dangerously hot or drop to a hard freeze once humidity and wind are folded in.

Herndon weather by month

How April compares with the rest of the year at a glance. April is the 7th-warmest and 6th-wettest month here — the current month is highlighted below.

MonthHigh / Low (°F)Rainfall (inches)Wet daysSnow daysDaylight (hours)Travel score
Jan42° / 28°3.08.639.60.3
Feb45° / 29°2.88.1310.51.1
Mar54° / 36°3.810211.73.3
Apr66° / 46°3.410.30.1135.8
May74° / 56°3.811.3014.16.5
Jun83° / 65°3.411.2014.75.5
Jul88° / 69°3.911.8014.54.4
Aug85° / 68°3.310.4013.55.1
Sep78° / 60°4.49.5012.36.7
Oct67° / 49°3.47.80116.5
Nov55° / 38°3.07.60.39.93.9
Dec46° / 32°3.59.12.19.31.3

Cloud cover in April

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 27% of the time in April.

Beyond those clear spells, partly cloudy skies cover about 15% of April, with mostly cloudy or overcast conditions the remaining 57%.

0%25%50%75%100%151015202530
Clearer (%)Cloudier (%)
14258
24357
34456
44456
54456
64555
74654
84654
94654
104654
114555
124456
134456
144357
154357
164258
174258
184258
194258
204159
214159
224060
234060
244159
254159
264159
274159
284159
294258
304258

Chance of precipitation in April

Any precipitationSnow

Herndon gets around 3.4 in of rain and snow over 10.3 wet days in April. The line is the day-by-day chance of measurable precipitation.

Day to day, the chance of measurable precipitation averages around 35% and peaks near 39% on the wettest days, and about 0 day brings snow.

0%10%20%30%40%50%151015202530
Rain chance (%)Snow chance (%)
1332
2332
3332
4331
5331
6331
7331
8321
9321
10321
11321
12321
13331
14330
15340
16340
17350
18350
19360
20360
21360
22370
23370
24370
25380
26380
27380
28390
29390
30390

Humidity in April

DryComfortableHumidMuggyOppressiveMiserable

Most of April feels dry — the stacked bands show each day's mix of comfort levels, read off the dew point.

By dew point, April lands in the dry band about 89% of days. It rarely turns muggy — the humid and sticky bands barely register.

0%25%50%75%100%151015202530
Dry (%)Comfortable (%)Humid (%)Muggy (%)
197300
297300
396400
496400
595500
694510
794510
893610
993610
1093610
1192710
1292710
1391810
1491810
1590910
1689920
1789920
1889920
19881020
20881020
21881020
22871030
23861130
24841141
25831241
26821251
27821251
28801361
29801361
30781471

Wind in April

Winds average 7 mph in April.

Across April, daily wind ranges from about 7 mph on the calmest days to 7 mph at its breeziest. It stays fairly steady from day to day.

0246810151015202530
Wind speed (mph)Feels
17calm
27calm
37calm
47calm
57calm
67calm
77calm
87calm
97calm
107calm
117calm
127calm
137calm
147calm
157calm
167calm
177calm
187calm
197calm
207calm
217calm
227calm
237calm
247calm
257calm
267calm
277calm
287calm
297calm
307calm

Sunrise & sunset in April

DaylightNight

Daylight runs from about 12 h 24 min at the start of April to 13 h 36 min by month's end. The lit band spans sunrise to sunset each day.

Days grow by about 72 minutes over April. Sunrise moves from 6:03 AM to 5:20 AM, and sunset from 6:26 PM to 6:54 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202530
Daylight (h)Sunrise (AM)Sunset (PM)
112.46:036:26
212.46:016:27
312.56:006:28
412.55:586:29
512.65:566:30
612.65:556:30
712.65:536:31
812.75:526:32
912.75:506:33
1012.85:486:34
1112.85:476:35
1212.95:456:36
1312.95:446:37
1412.95:426:38
1513.05:416:39
1613.05:396:40
1713.15:386:41
1813.15:366:42
1913.15:356:43
2013.25:336:44
2113.25:326:45
2213.35:306:46
2313.35:296:47
2413.35:286:48
2513.45:266:49
2613.45:256:50
2713.55:246:51
2813.55:226:52
2913.55:216:53
3013.65:206:54

Solar energy in April

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in April, about 5.2 kWh/m².

For context, solar energy here swings from a low near 1.95 kWh/m² to a high of 6.15 kWh/m² in June across the year — April's 5.2 kWh/m² falls in the middle.

0246151015202530
Solar energy (kWh/m²)Level
14.7Bright
24.8Bright
34.8Bright
44.9Bright
54.9Bright
64.9Bright
75.0Bright
85.0Bright
95.0Bright
105.1Bright
115.1Bright
125.1Bright
135.1Bright
145.2Bright
155.2Bright
165.2Bright
175.2Bright
185.2Bright
195.3Bright
205.3Bright
215.3Bright
225.3Bright
235.3Bright
245.3Bright
255.4Bright
265.4Bright
275.4Bright
285.4Bright
295.4Bright
305.5Bright
Planning a trip in April

Is April a good time to visit Herndon?

Our two travel scores rate April for general sightseeing and for beach or pool weather — 0 (poor) to 10 (ideal).

5.8
Sightseeing
4th-best month of the year
2.3
Beach & pool
7th-best month of the year

April is a reasonable time to visit Herndon for sightseeing.

What to pack for Herndon in April

From April's temperature range, rain chance, sun and wind — what's worth putting in the bag.

In April, Herndon sees daytime highs around 66°F and nights near 46°F. Worth packing: a warm layer, rain gear and sun protection. About 10 days see rain.

a warm layerrain gearsun protection

UV index in Herndon in April

LowModerateHighVery highExtreme

Clear-sky midday UV in April peaks around 6 — enough to warrant sun protection. The full-year curve, shaded by WHO exposure level, is below.

Under clear skies, the midday UV index in Herndon peaks around July 11 at about 9 (very high) — sunscreen, a hat and midday shade are essential. It bottoms out near December 19 at about 2 (low).

The index reaches 3 or more — the level where the WHO recommends sun protection — in 9 months of the year.

025710JanFebMarAprMayJunJulAugSepOctNovDecModerateHighVery highHighModerateLowJul 11UV 9Dec 19UV 2
UV index (midday)Level
Jan2Moderate
Feb3Moderate
Mar5High
Apr6High
May8Very high
Jun9Very high
Jul9Very high
Aug7High
Sep6High
Oct4Moderate
Nov3Moderate
Dec2Low

Air quality in Herndon in April

GoodModeratePoorUnhealthyVery unhealthy

Average fine-particle pollution (PM2.5) through the year — so you can see where April falls, not just the annual average.

Air quality in Herndon is worst in July — around 17 µg/m³ PM2.5 (moderate), about 1.9× the cleanest month (November, 9 µg/m³).

Modeled monthly averages (CAMS reanalysis, 2015–2024).

01020JanFebMarAprMayJunJulAugSepOctNovDecGoodModerateGoodJul 1317 µg/m³Nov 129 µg/m³
PM2.5 (µg/m³)Level
Jan11Good
Feb12Moderate
Mar13Moderate
Apr13Moderate
May15Moderate
Jun16Moderate
Jul17Moderate
Aug15Moderate
Sep12Moderate
Oct9Good
Nov9Good
Dec10Good
Location & terrain

Where is Herndon?

Herndon sits at 39.0°N, 77.4°W, 361 ft above sea level, in United States. The nearest listed city is Reston, 2.5 mi away.

Topography around Herndon

How much the land rises and falls, and what covers it, within 2, 10 and 50 miles of Herndon.

Within 2 miles, the terrain around Herndon has only modest variations in elevation — a maximum elevation change of 505 ft around an average of 377 ft above sea level; within 10 miles, only modest variations in elevation — a maximum elevation change of 558 ft; within 50 miles, large variations in elevation — a maximum elevation change of 3,615 ft.

The land around Herndon is covered by trees (57%) and artificial surfaces (35%) within 2 miles, trees (67%) within 10 miles, and trees (65%) within 50 miles.

2 miles
505 ft
10 miles
558 ft
50 miles
3,615 ft
treesgrasslandcroplandartificial surfacesbare terrainwater
April weather nearby: Reston 2.5 mi · Oak Hill 3.1 mi · Sterling 3.1 mi · Great Falls 5.6 mi · Chantilly 5.6 mi · Wolf Trap 5.6 mi · South Riding 7.5 mi · Ashburn 7.5 mi

United States travel facts

Power plugs
Type A / B
120 V · 60 Hz
Prices
≈ 100% of US
price level, 2025
GDP per capita
$90,027
2025
Happiness
6.8 / 10
World Happiness, 2025
Safe drinking water
98%
of population, 2024
Homicide rate
5.8
per 100k, 2023
Road deaths
12.7
per 100k/yr, 2019
Income group
High
World Bank
Religion
Protestant 47%unaffiliated 23%Roman Catholic 21%Jewish 2%

Sources: World Bank, US State Department, World Happiness Report, WHO/UNICEF, EF EPI, CIA World Factbook.

Data sources

Temperature, precipitation, cloud, humidity, wind and solar figures are a 1991–2020 climatology for Herndon (38.9695°, -77.3861°, elevation 361 ft), computed from hourly ERA5 reanalysis — contains modified Copernicus Climate Change Service information. Sun figures are astronomical calculations, not observations. City data © GeoNames, CC BY 4.0. Map outlines from Natural Earth (public domain); interactive map © Google. UV index is derived from CAMS (Copernicus Atmosphere Monitoring Service) clear-sky UV data — contains modified Copernicus Atmosphere Monitoring Service information. Monthly air-quality (PM2.5) seasonality is from the CAMS EAC4 reanalysis (Copernicus Atmosphere Monitoring Service), scaled to the WHO annual mean where available. Topography is sampled from the Copernicus DEM GLO-90 elevation model (© ESA/Airbus) and ESA WorldCover 2021 land cover (CC BY 4.0).