McKinleyville weather in September

In September, McKinleyville sees average daytime highs of 65°F and overnight lows near 51°F, with 0.8 in of rain across 2.6 wet days and about 12.3 hours of daylight. It is the 3rd-warmest and 10th-wettest month of the year here.

Day-to-day highs hold fairly steady near 65°F through the month. The sky is clear or mostly clear about 66% of the time in September, and the air most often feels dry.

Daylight stretches from about 13 hours at the start of September to 11 h 36 min by month's end. Set against the rest of the year, September is McKinleyville's 2nd-clearest and 12th-windiest month. For the whole year in context, see McKinleyville's year-round climate.

Daytime high
65°
3rd warmest
Overnight low
51°
10th coldest
Rainfall
0.8 in
2.6 wet days
Daylight
12 h 18 min
6:03 AM – 6:19 PM
Cloud cover
30%
2nd clearest
Wind
5 mph
12th windiest
Solar energy
5.5 kWh/m²
Travel score
7.6
out of 10

McKinleyville is census-designated place in Humboldt County, California, United States.

Density
279/km²
people per km²

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

Temperature in September

Average highAverage lowShaded bands: 10–90% of days

Day-to-day highs hold fairly steady near 65°F through the month.

A typical September day in McKinleyville reaches about 65°F in the afternoon and slips back to 51°F overnight — a 14°F spread between the day's warmth and the night's chill. On most days the high lands between 60°F and 73°F. Set against its neighbours, September runs on par with August and about 5°F warmer than October.

40°50°60°70°80°151015202530
Avg high (°F)Avg low (°F)
16753
26753
36753
46753
56653
66652
76652
86652
96652
106652
116652
126652
136652
146652
156552
166551
176551
186551
196551
206551
216551
226551
236551
246551
256551
266551
276550
286450
296450
306450

McKinleyville weather by month

How September compares with the rest of the year at a glance. September is the 3rd-warmest and 10th-wettest month here — the current month is highlighted below.

MonthHigh / Low (°F)Rainfall (inches)Wet daysSnow daysDaylight (hours)Travel score
Jan51° / 41°9.315.31.79.42.2
Feb52° / 41°7.413.52.410.42.4
Mar53° / 42°7.815.12.611.72.6
Apr55° / 44°4.812.10.713.13.2
May58° / 47°2.67.4014.34.6
Jun62° / 50°1.03.7014.96.3
Jul66° / 53°0.10.7014.67.9
Aug67° / 53°0.20.9013.68.0
Sep65° / 51°0.82.6012.37.6
Oct61° / 48°3.56.5010.95.8
Nov54° / 44°6.912.60.49.73.2
Dec51° / 41°11.215.51.89.12.1

Cloud cover in September

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 66% of the time in September.

Beyond those clear spells, partly cloudy skies cover about 17% of September, with mostly cloudy or overcast conditions the remaining 17%. Skies tend to cloud over as the month goes on.

0%25%50%75%100%151015202530
Clearer (%)Cloudier (%)
18812
28812
38812
48812
58614
68614
78515
88515
98515
108317
118317
128218
138218
148218
158218
168119
178119
188218
198218
208218
218218
228218
238218
248218
258218
268119
278119
288020
298020
307921

Chance of precipitation in September

Any precipitation

McKinleyville gets around 0.8 in of rain over 2.6 wet days in September. The line is the day-by-day chance of measurable precipitation.

Day to day, the chance of measurable rain averages around 9% and peaks near 15% on the wettest days. The odds climb toward the end of the month.

0%10%20%30%151015202530
Rain chance (%)
14
23
33
44
54
64
75
85
96
107
117
128
139
149
1510
1610
1711
1811
1912
2012
2113
2213
2313
2413
2514
2614
2714
2814
2914
3015

Humidity in September

DryComfortableHumidMuggyOppressiveMiserable

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

By dew point, September lands in the dry band about 91% of days. It rarely turns muggy — the humid and sticky bands barely register.

0%25%50%75%100%151015202530
Dry (%)Comfortable (%)
18614
28713
38713
48812
58812
68911
78911
89010
99010
10919
11919
12919
13919
14928
15928
16928
17928
18928
19928
20928
21937
22937
23937
24937
25946
26946
27946
28955
29955
30964

Wind in September

Winds average 5 mph in September, the calmest month.

Across September, daily wind ranges from about 5 mph on the calmest days to 5 mph at its breeziest. It stays fairly steady from day to day.

0246810151015202530
Wind speed (mph)Feels
15calm
25calm
35calm
45calm
55calm
65calm
75calm
85calm
95calm
105calm
115calm
125calm
135calm
145calm
155calm
165calm
175calm
185calm
195calm
205calm
215calm
225calm
235calm
245calm
255calm
265calm
275calm
285calm
295calm
305calm

Sunrise & sunset in September

DaylightNight

Daylight runs from about 13 hours at the start of September to 11 h 36 min by month's end. The lit band spans sunrise to sunset each day.

Days shrink by about 84 minutes over September. Sunrise moves from 5:47 AM to 6:17 AM, and sunset from 6:45 PM to 5:54 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202530
Daylight (h)Sunrise (AM)Sunset (PM)
113.05:476:45
212.95:486:43
312.95:496:41
412.85:506:40
512.85:516:38
612.75:526:36
712.75:546:35
812.65:556:33
912.65:566:31
1012.55:576:29
1112.55:586:28
1212.55:596:26
1312.46:006:24
1412.46:016:22
1512.36:026:21
1612.36:036:19
1712.26:046:17
1812.26:056:15
1912.16:066:13
2012.16:076:12
2112.06:086:10
2212.06:096:08
2311.96:106:06
2411.96:116:05
2511.86:126:03
2611.86:136:01
2711.86:145:59
2811.76:155:58
2911.76:165:56
3011.66:175:54

Solar energy in September

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in September, about 5.5 kWh/m².

For context, solar energy here swings from a low near 1.64 kWh/m² to a high of 7.8 kWh/m² in July across the year — September's 5.5 kWh/m² falls in the middle.

0246151015202530
Solar energy (kWh/m²)Level
16.3Intense
26.2Intense
36.2Intense
46.1Intense
56.1Intense
66.0Intense
76.0Bright
85.9Bright
95.8Bright
105.8Bright
115.7Bright
125.7Bright
135.6Bright
145.5Bright
155.5Bright
165.4Bright
175.4Bright
185.3Bright
195.3Bright
205.2Bright
215.2Bright
225.1Bright
235.1Bright
245.0Bright
255.0Bright
264.9Bright
274.9Bright
284.8Bright
294.8Bright
304.7Bright
Planning a trip in September

Hazard calendar for McKinleyville

In seasonPeak

None of McKinleyville's seasonal hazards are active in September. The full-year calendar below shows when the rainy season, cyclone risk and dust haze do peak.

McKinleyville's rainy season runs November–March, when most of the year's rain falls.

Rainy season
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec

Is September a good time to visit McKinleyville?

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

7.6
Sightseeing
3rd-best month of the year
3.0
Beach & pool
3rd-best month of the year

September is one of the better times to visit McKinleyville for general sightseeing.

What to pack for McKinleyville in September

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

In September, McKinleyville sees daytime highs around 65°F and nights near 51°F. Worth packing: sun protection.

sun protection

Sea temperature near McKinleyville in September

The nearest coast averages about 55°F in September — the other half of the beach question. The full-year curve and swim-comfort zones are below.

The sea offshore is warmest in August at about 55°F and coldest in March near 51°F.

The water stays below 68°F all year — cool enough that most swimmers want a wetsuit.

50°52°54°56°JanFebMarAprMayJunJulAugSepOctNovDecbracing
Sea temperature (°F)Comfort
Jan52Bracing
Feb52Bracing
Mar51Bracing
Apr52Bracing
May52Bracing
Jun53Bracing
Jul54Bracing
Aug55Bracing
Sep55Bracing
Oct54Bracing
Nov53Bracing
Dec53Bracing

UV index in McKinleyville in September

LowModerateHighVery highExtreme

Clear-sky midday UV in September 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 McKinleyville peaks around June 21 at about 9 (very high) — sunscreen, a hat and midday shade are essential. It bottoms out near December 15 at about 2 (low).

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

025710JanFebMarAprMayJunJulAugSepOctNovDecModerateHighVery highHighModerateLowJun 21UV 9Dec 15UV 2
UV index (midday)Level
Jan2Low
Feb3Moderate
Mar5Moderate
Apr6High
May9Very high
Jun10Very high
Jul9Very high
Aug8Very high
Sep5High
Oct5Moderate
Nov2Low
Dec2Low

Air quality in McKinleyville in September

GoodModeratePoorUnhealthyVery unhealthy

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

Air quality in McKinleyville is worst in September — around 154 µg/m³ PM2.5 (very unhealthy), about 39.6× the cleanest month (January, 4 µg/m³).

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

0306090120150180JanFebMarAprMayJunJulAugSepOctNovDecGoodUnhealthyUnhealthyGoodSep 10151 µg/m³Jan 134 µg/m³
PM2.5 (µg/m³)Level
Jan4Good
Feb7Good
Mar6Good
Apr7Good
May6Good
Jun6Good
Jul17Moderate
Aug137Unhealthy
Sep154Very unhealthy
Oct13Moderate
Nov6Good
Dec5Good
Location & terrain

Where is McKinleyville?

McKinleyville sits at 40.9°N, 124.1°W, 144 ft above sea level, in United States. The nearest listed city is Arcata, 5.6 mi away.

Topography around McKinleyville

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

Within 2 miles, the terrain around McKinleyville has only modest variations in elevation — a maximum elevation change of 643 ft around an average of 180 ft above sea level; within 10 miles, large variations in elevation — a maximum elevation change of 3,038 ft; within 50 miles, very significant variations in elevation — a maximum elevation change of 7,415 ft.

The land around McKinleyville is covered by trees (50%) and grassland (23%) within 2 miles, trees (48%) and water (41%) within 10 miles, and trees (67%) and water (27%) within 50 miles.

2 miles
643 ft
10 miles
3,038 ft
50 miles
7,415 ft
treesgrasslandcroplandartificial surfacesbare terrainwater
September weather nearby: Arcata 5.6 mi · Bayside 7.5 mi · Eureka 11 mi · Redding 93 mi · Grants Pass 111 mi · Ashland 112 mi · Medford 114 mi · Central Point 116 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 McKinleyville (40.9465°, -124.1006°, elevation 144 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. Sea temperatures are the NOAA OISST v2.1 1991–2020 monthly climatology (public domain), sampled at the nearest ocean point. 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).