Yellowknife weather in September

In September, Yellowknife sees average daytime highs of 11°C and overnight lows near 5°C, with 40 mm of precipitation across 8.2 wet days and about 12.6 hours of daylight. It is the 4th-warmest and 2nd-wettest month of the year here.

Highs ease over the month, from about 14°C in the first days to 7°C by the end. The sky is clear or mostly clear about 15% of the time in September, and the air most often feels dry.

Daylight stretches from about 14 h 06 min at the start of September to 11 h 06 min by month's end. Set against the rest of the year, September is Yellowknife's 8th-clearest and 1st-windiest month. For the whole year in context, see Yellowknife's year-round climate.

Daytime high
11°
4th warmest
Overnight low
9th coldest
Precipitation
40 mm
8.2 wet days
Daylight
12 h 36 min
6:14 AM – 6:50 PM
Cloud cover
73%
8th clearest
Wind
14 km/h
1st windiest
Solar energy
2.42 kWh/m²
Travel score
2.5
out of 10

Yellowknife is capital and largest city of the Northwest Territories, Canada.

Air quality
Excellent
PM2.5 4 µg/m³ · 2019
Density
149/km²
people per km²
Founded
1970

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

Temperature in September

Average highAverage lowShaded bands: 10–90% of days

Highs ease over the month, from about 14°C in the first days to 7°C by the end.

A typical September day in Yellowknife reaches about 11°C in the afternoon and slips back to 5°C overnight — a 6°C spread between the day's warmth and the night's chill. On most days the high lands between 5°C and 16°C. Set against its neighbours, September runs about 7°C cooler than August and about 9°C warmer than October.

-5°10°15°20°151015202530
Avg high (°C)Avg low (°C)
1148
2148
3147
4147
5137
6137
7137
8136
9126
10126
11126
12125
13115
14115
15115
16115
17104
18104
19104
20104
2194
2293
2393
2483
2583
2682
2772
2872
2972
3061

How September really feels in Yellowknife

Once humidity and wind are folded in, September averages 0 days that feel above 32°C and 9 that feel at or below 0°C — the comfort signal a plain temperature reading hides.

Days feeling ≥ 32°C
0
heat index over the day's high
Days feeling ≤ C
9
wind chill below the day's low

The story in September is cold — wind chill drags the overnight "feels like" below the raw low.

Yellowknife weather by month

How September compares with the rest of the year at a glance. September is the 4th-warmest and 2nd-wettest month here — the current month is highlighted below.

MonthHigh / Low (°C)Rainfall (mm)Wet daysSnow daysDaylight (hours)Travel score
Jan-22° / -28°103.44.45.60.0
Feb-19° / -26°62.12.88.20.0
Mar-12° / -21°103.24.211.30.0
Apr-1° / -11°113.12.514.40.0
May10° / 194.61.417.42.5
Jun18° / 255.3019.36.2
Jul21° / 13°377.3018.56.8
Aug18° / 11°469.2015.85.7
Sep11° / 408.20.512.62.5
Oct / -3°246.44.39.50.0
Nov-10° / -16°154.666.50.0
Dec-18° / -24°103.44.54.70.0

Cloud cover in September

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 15% of the time in September.

Beyond those clear spells, partly cloudy skies cover about 11% of September, with mostly cloudy or overcast conditions the remaining 74%.

0%25%50%75%100%151015202530
Clearer (%)Cloudier (%)
13070
23070
33070
42971
52971
62971
72971
82872
92773
102872
112872
122872
132773
142773
152773
162773
172674
182674
192674
202476
212476
222476
232476
242476
252278
262278
272278
282179
292080
302080

Chance of precipitation in September

Any precipitationSnow

Yellowknife gets around 40 mm of rain and snow over 8.2 wet days in September. The line is the day-by-day chance of measurable precipitation.

Day to day, the chance of measurable precipitation averages around 27% and peaks near 29% on the wettest days, and about 1 day brings snow.

0%10%20%30%40%151015202530
Rain chance (%)Snow chance (%)
1290
2290
3290
4290
5290
6280
7280
8280
9280
10270
11270
12270
13271
14271
15271
16271
17261
18262
19262
20263
21263
22263
23264
24264
25254
26255
27255
28245
29246
30246

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 100% of days. It rarely turns muggy — the humid and sticky bands barely register.

0%25%50%75%100%151015202530
Dry (%)Comfortable (%)
1982
2991
3991
4991
5991
6991
71000
81000
91000
101000
111000
121000
131000
141000
151000
161000
171000
181000
191000
201000
211000
221000
231000
241000
251000
261000
271000
281000
291000
301000

Wind in September

Winds average 14 km/h in September, the windiest month of the year.

Across September, daily wind ranges from about 13 km/h on the calmest days to 14 km/h at its breeziest. It stays fairly steady from day to day.

05101520151015202530
Wind speed (km/h)Feels
113light breeze
213light breeze
313light breeze
413light breeze
513light breeze
613light breeze
713light breeze
813light breeze
913light breeze
1014light breeze
1114light breeze
1214light breeze
1314light breeze
1414light breeze
1514light breeze
1614light breeze
1714light breeze
1814light breeze
1914light breeze
2014light breeze
2114light breeze
2214light breeze
2314light breeze
2414light breeze
2514light breeze
2614light breeze
2714light breeze
2814light breeze
2914light breeze
3014light breeze

Sunrise & sunset in September

DaylightNight

Daylight runs from about 14 h 06 min at the start of September to 11 h 06 min by month's end. The lit band spans sunrise to sunset each day.

Days shrink by about 180 minutes over September. Sunrise moves from 5:33 AM to 6:52 AM, and sunset from 7:41 PM to 6:01 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202530
Daylight (h)Sunrise (AM)Sunset (PM)
114.15:337:41
214.05:367:38
313.95:397:34
413.85:417:31
513.75:447:28
613.65:477:24
713.55:507:21
813.45:527:17
913.35:557:14
1013.25:587:10
1113.16:007:07
1213.06:037:03
1312.96:067:00
1412.86:096:57
1512.76:116:53
1612.66:146:50
1712.56:176:46
1812.46:196:43
1912.36:226:39
2012.26:256:36
2112.16:286:32
2212.06:306:29
2311.96:336:25
2411.86:366:22
2511.76:396:18
2611.66:416:15
2711.56:446:12
2811.46:476:08
2911.36:506:05
3011.16:526:01

Solar energy in September

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in September, about 2.42 kWh/m².

For context, solar energy here swings from a low near 0.13 kWh/m² to a high of 6.39 kWh/m² in June across the year — September's 2.42 kWh/m² falls in the middle.

01234151015202530
Solar energy (kWh/m²)Level
13.1Moderate
23.1Moderate
33.1Moderate
43.0Moderate
53.0Moderate
62.9Moderate
72.9Moderate
82.8Moderate
92.8Moderate
102.7Moderate
112.7Moderate
122.6Moderate
132.5Moderate
142.5Moderate
152.5Moderate
162.4Moderate
172.3Moderate
182.3Moderate
192.2Moderate
202.2Moderate
212.1Moderate
222.1Moderate
232.0Moderate
242.0Dim
251.9Dim
261.9Dim
271.8Dim
281.8Dim
291.7Dim
301.7Dim
Planning a trip in September

Is September a good time to visit Yellowknife?

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

2.5
Sightseeing
4th-best month of the year
0.0
Beach & pool
5th-best month of the year

September is a weaker month for outdoor sightseeing in Yellowknife.

What to pack for Yellowknife in September

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

In September, Yellowknife sees daytime highs around 11°C and nights near 5°C. Pack a warm layer. Worth having: rain gear. About 8 days see rain.

a warm layerrain gear

UV index in Yellowknife in September

LowModerateHighVery highExtreme

Clear-sky midday UV in September peaks around 2. The full-year curve, shaded by WHO exposure level, is below.

Under clear skies, the midday UV index in Yellowknife peaks around June 15 at about 4 (moderate) — a little sun protection helps at midday. It bottoms out near January 1 at about 0 (low).

The index reaches 3 or more — the level where the WHO recommends sun protection — in 4 months of the year.

025710JanFebMarAprMayJunJulAugSepOctNovDecLowModerateLowJun 15UV 4Jan 1UV 0
UV index (midday)Level
Jan0Low
Feb1Low
Mar1Low
Apr3Moderate
May4Moderate
Jun4Moderate
Jul4Moderate
Aug3Moderate
Sep2Low
Oct1Low
Nov0Low
Dec0Low

Air quality in Yellowknife 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 Yellowknife is worst in August — around 22 µg/m³ PM2.5 (moderate), about 224.0× the cleanest month (January, 0 µg/m³).

Seasonal pattern from CAMS reanalysis, scaled to Yellowknife's WHO annual average of 4 µg/m³.

0102030JanFebMarAprMayJunJulAugSepOctNovDecGoodModerateGoodAug 1421 µg/m³Jan 10 µg/m³
PM2.5 (µg/m³)Level
Jan0Good
Feb0Good
Mar1Good
Apr2Good
May2Good
Jun4Good
Jul13Moderate
Aug22Moderate
Sep3Good
Oct0Good
Nov0Good
Dec0Good
Location & terrain

Where is Yellowknife?

Yellowknife sits at 62.5°N, 114.4°W, 252 m above sea level, in Canada. The nearest listed city is Fort McMurray, 659 km away.

Fort McMurrayFort St. JohnGrande PrairieSt. AlbertEdmontonWîhkwêntôwinStony PlainSpruce Grove

Topography around Yellowknife

How much the land rises and falls, and what covers it, within 3, 16 and 80 km of Yellowknife.

Within 3 km, the terrain around Yellowknife has only modest variations in elevation — a maximum elevation change of 56 m around an average of 180 m above sea level; within 16 km, only modest variations in elevation — a maximum elevation change of 97 m; within 80 km, only modest variations in elevation — a maximum elevation change of 220 m.

The land around Yellowknife is covered by trees (43%) and water (31%) within 3 km, trees (60%) and water (29%) within 16 km, and trees (50%) and water (40%) within 80 km.

3 km
56 m
16 km
97 m
80 km
220 m
treesshrubsgrasslandartificial surfacesbare terrainwatermoss and lichen
September weather nearby: Fort McMurray 659 km · Fort St. John 781 km · Grande Prairie 849 km · St. Albert 982 km · Edmonton 991 km · Wîhkwêntôwin 992 km · Stony Plain 992 km · Spruce Grove 992 km

Canada travel facts

Travel advisory
Level 1
Exercise Normal Precautions
Power plugs
Type A / B
120 V · 60 Hz
Prices
≈ 83% of US
price level, 2025
GDP per capita
$55,698
2025
Happiness
6.7 / 10
World Happiness, 2025
Safe drinking water
97%
of population, 2024
Homicide rate
2
per 100k, 2023
Road deaths
5.3
per 100k/yr, 2019
Income group
High
World Bank
Religion
Christian 53%none 35%Muslim 5%Hindu 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 Yellowknife (62.4541°, -114.3725°, elevation 252 m), 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).