Merrimack weather in August

In August, Merrimack sees average daytime highs of 80°F and overnight lows near 62°F, with 3.4 in of rain across 9.6 wet days and about 13.7 hours of daylight. It is the 2nd-warmest and 9th-wettest month of the year here.

Highs ease over the month, from about 82°F in the first days to 79°F by the end. The sky is clear or mostly clear about 31% of the time in August, and the air most often feels comfortable.

Daylight stretches from about 14 h 24 min at the start of August to 13 h 06 min by month's end. Set against the rest of the year, August is Merrimack's 4th-clearest and 12th-windiest month. For the whole year in context, see Merrimack's year-round climate.

Daytime high
80°
2nd warmest
Overnight low
62°
11th coldest
Rainfall
3.4 in
9.6 wet days
Daylight
13 h 48 min
4:57 AM – 6:43 PM
Cloud cover
57%
4th clearest
Wind
6 mph
12th windiest
Solar energy
5.21 kWh/m²
Travel score
6.6
out of 10

Merrimack is town in New Hampshire, United States.

Founded
1673

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

Temperature in August

Average highAverage lowShaded bands: 10–90% of days

Highs ease over the month, from about 82°F in the first days to 79°F by the end.

A typical August day in Merrimack reaches about 80°F in the afternoon and slips back to 62°F overnight — a 19°F spread between the day's warmth and the night's chill. On most days the high lands between 72°F and 89°F. Set against its neighbours, August runs about 2°F cooler than July and about 8°F warmer than September.

50°60°70°80°90°151015202531
Avg high (°F)Avg low (°F)
18264
28264
38264
48264
58263
68263
78263
88263
98163
108163
118163
128163
138162
148162
158162
168162
178062
188062
198062
208061
218061
228061
238061
248061
258060
267960
277960
287960
297960
307859
317859

How August really feels in Merrimack

Once humidity and wind are folded in, August 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

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

Merrimack weather by month

How August compares with the rest of the year at a glance. August is the 2nd-warmest and 9th-wettest month here — the current month is highlighted below.

MonthHigh / Low (°F)Rainfall (inches)Wet daysSnow daysDaylight (hours)Travel score
Jan34° / 19°3.19.66.79.20.0
Feb36° / 20°3.08.4610.20.0
Mar44° / 28°4.110.95.411.60.8
Apr57° / 39°3.710.51.513.13.8
May67° / 48°3.210.8014.46.0
Jun77° / 58°3.510.8015.16.5
Jul82° / 64°3.410.3014.86.0
Aug80° / 62°3.49.6013.76.6
Sep73° / 54°3.48012.37.0
Oct61° / 44°3.89.30.310.85.1
Nov49° / 34°3.49.41.49.52.0
Dec39° / 25°4.110.35.58.90.1

Cloud cover in August

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 31% of the time in August.

Beyond those clear spells, partly cloudy skies cover about 20% of August, with mostly cloudy or overcast conditions the remaining 49%. Skies tend to open up as the month goes on.

0%25%50%75%100%151015202531
Clearer (%)Cloudier (%)
14951
25050
35149
45050
55149
65149
75050
85050
94852
104852
114951
124852
134951
144951
154951
164951
175050
185050
195149
205149
215347
225347
235446
245545
255545
265545
275545
285545
295545
305545
315545

Chance of precipitation in August

Any precipitation

Merrimack gets around 3.4 in of rain over 9.6 wet days in August. The line is the day-by-day chance of measurable precipitation.

Day to day, the chance of measurable rain averages around 31% and peaks near 35% on the wettest days. The odds ease toward the end of the month.

0%10%20%30%40%50%151015202531
Rain chance (%)
135
235
334
434
534
634
734
834
934
1034
1134
1234
1334
1433
1533
1632
1732
1831
1931
2030
2129
2228
2328
2427
2526
2626
2725
2825
2924
3024
3124

Humidity in August

DryComfortableHumidMuggyOppressiveMiserable

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

By dew point, August lands in the comfortable band about 26% of days. Sticky, muggy-or-worse air turns up on roughly 23% of them.

0%25%50%75%100%151015202531
Dry (%)Comfortable (%)Humid (%)Muggy (%)Oppressive (%)
1192329226
2202329226
3202429226
4202428226
5212428216
6212428216
7212428216
8212528206
9212528206
10222528205
11222528205
12222528205
13232627204
14232627204
15232727204
16232726203
17242826203
18242825193
19252825193
20262924192
21272923192
22282823182
23302822182
24312821172
25332820172
26342819162
27352919162
28362818152
29372818152
30382818142
31392817142

Wind in August

Winds average 6 mph in August, the calmest month.

Across August, daily wind ranges from about 6 mph on the calmest days to 6 mph at its breeziest. It stays fairly steady from day to day.

0246810151015202531
Wind speed (mph)Feels
16calm
26calm
36calm
46calm
56calm
66calm
76calm
86calm
96calm
106calm
116calm
126calm
136calm
146calm
156calm
166calm
176calm
186calm
196calm
206calm
216calm
226calm
236calm
246calm
256calm
266calm
276calm
286calm
296calm
306calm
316calm

Sunrise & sunset in August

DaylightNight

Daylight runs from about 14 h 24 min at the start of August to 13 h 06 min by month's end. The lit band spans sunrise to sunset each day.

Days shrink by about 78 minutes over August. Sunrise moves from 4:41 AM to 5:14 AM, and sunset from 7:03 PM to 6:18 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202531
Daylight (h)Sunrise (AM)Sunset (PM)
114.44:417:03
214.34:427:02
314.34:437:01
414.34:447:00
514.24:456:58
614.24:466:57
714.14:476:56
814.14:486:54
914.14:496:53
1014.04:506:52
1114.04:526:50
1213.94:536:49
1313.94:546:47
1413.94:556:46
1513.84:566:45
1613.84:576:43
1713.74:586:41
1813.74:596:40
1913.65:006:38
2013.65:026:37
2113.55:036:35
2213.55:046:34
2313.45:056:32
2413.45:066:30
2513.45:076:29
2613.35:086:27
2713.35:096:25
2813.25:106:23
2913.25:126:22
3013.15:136:20
3113.15:146:18

Solar energy in August

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in August, about 5.21 kWh/m².

For context, solar energy here swings from a low near 1.58 kWh/m² to a high of 5.88 kWh/m² in July across the year — August's 5.21 kWh/m² falls in the middle.

0246151015202531
Solar energy (kWh/m²)Level
15.5Bright
25.5Bright
35.5Bright
45.4Bright
55.4Bright
65.4Bright
75.4Bright
85.3Bright
95.3Bright
105.3Bright
115.3Bright
125.2Bright
135.2Bright
145.2Bright
155.2Bright
165.2Bright
175.1Bright
185.1Bright
195.1Bright
205.1Bright
215.1Bright
225.1Bright
235.1Bright
245.0Bright
255.0Bright
265.0Bright
275.0Bright
284.9Bright
294.9Bright
304.9Bright
314.8Bright
Planning a trip in August

Hazard calendar for Merrimack

In seasonPeak

In August, Merrimack sits inside its atlantic hurricane season. The full year is below, with each hazard's peak months called out.

Merrimack sits in the Atlantic hurricane belt; the season peaks August–October.

Atlantic hurricane
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec

Is August a good time to visit Merrimack?

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

6.6
Sightseeing
2nd-best month of the year
6.7
Beach & pool
2nd-best month of the year

August is a reasonable time to visit Merrimack for sightseeing. The water and warmth also suit a beach or pool day.

What to pack for Merrimack in August

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

In August, Merrimack sees daytime highs around 80°F and nights near 62°F. Worth packing: light clothes, rain gear and sun protection. About 10 days see rain.

light clothesrain gearsun protection

UV index in Merrimack in August

LowModerateHighVery highExtreme

Clear-sky midday UV in August peaks around 5 — enough to warrant sun protection. The full-year curve, shaded by WHO exposure level, is below.

Under clear skies, the midday UV index in Merrimack peaks around July 10 at about 7 (very high) — sunscreen and a hat are worth it in the middle of the day. It bottoms out near December 23 at about 1 (low).

The index reaches 3 or more — the level where the WHO recommends sun protection — in 8 months of the year.

025710JanFebMarAprMayJunJulAugSepOctNovDecLowModerateHighVery highHighHighModerateLowJul 10UV 7Dec 23UV 1
UV index (midday)Level
Jan1Low
Feb3Moderate
Mar4Moderate
Apr5High
May7Very high
Jun7High
Jul7Very high
Aug5Moderate
Sep6High
Oct3Moderate
Nov2Moderate
Dec1Low

Air quality in Merrimack in August

GoodModeratePoorUnhealthyVery unhealthy

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

Air quality in Merrimack is worst in July — around 16 µg/m³ PM2.5 (moderate), about 2.0× the cleanest month (November, 8 µg/m³).

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

01020JanFebMarAprMayJunJulAugSepOctNovDecGoodModerateGoodJul 1715 µg/m³Nov 188 µg/m³
PM2.5 (µg/m³)Level
Jan9Good
Feb13Moderate
Mar13Moderate
Apr13Moderate
May14Moderate
Jun13Moderate
Jul16Moderate
Aug14Moderate
Sep11Good
Oct9Good
Nov8Good
Dec9Good
Location & terrain

Where is Merrimack?

Merrimack sits at 42.9°N, 71.5°W, 154 ft above sea level, in United States. The nearest listed city is Bedford, 5.6 mi away.

Topography around Merrimack

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

Within 2 miles, the terrain around Merrimack has only modest variations in elevation — a maximum elevation change of 289 ft around an average of 203 ft above sea level; within 10 miles, significant variations in elevation — a maximum elevation change of 1,227 ft; within 50 miles, large variations in elevation — a maximum elevation change of 3,176 ft.

The land around Merrimack is covered by trees (73%) within 2 miles, trees (77%) within 10 miles, and trees (82%) within 50 miles.

2 miles
289 ft
10 miles
1,227 ft
50 miles
3,176 ft
treesgrasslandcroplandartificial surfaceswaterwetland
August weather nearby: Bedford 5.6 mi · Nashua 6.8 mi · Derry 8.7 mi · Manchester 9.3 mi · Derry Village 9.3 mi · Salem 16 mi · Dracut 17 mi · Methuen 18 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 Merrimack (42.8651°, -71.4934°, elevation 154 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. Tropical-cyclone seasons are the published climatological basin seasons (NOAA National Hurricane Center / regional warning centres). 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).