Semnan weather in September

In September, Semnan sees average daytime highs of 30°C and overnight lows near 18°C, with 2 mm of rain across 0.5 wet days and about 12.2 hours of daylight. It is the 4th-warmest and 9th-wettest month of the year here.

Highs ease over the month, from about 32°C in the first days to 28°C by the end. The sky is clear or mostly clear about 94% of the time in September, and the air most often feels dry.

Daylight stretches from about 12 h 48 min at the start of September to 11 h 42 min by month's end. Set against the rest of the year, September is Semnan's 2nd-clearest and 6th-windiest month. For the whole year in context, see Semnan's year-round climate.

Daytime high: 30°; 4th warmest
Overnight low: 18°; 9th coldest
Rainfall: 2 mm; 0.5 wet days
Daylight: 12 h 12 min; 5:44 AM – 5:57 PM
Cloud cover: 10%; 2nd clearest
Wind: 11 km/h; 6th windiest
Solar energy: 5.89 kWh/m²
Travel score: 6.8; out of 10

Semnan is city in Semnan Province, Iran.

Air quality: Elevated; PM10 48.4 µg/m³ · 2014
Founded: ~240 CE

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

← August Semnan year-round climate October →Best places to visit in September

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

Temperature in September

Average highAverage lowShaded bands: 10–90% of days

Highs ease over the month, from about 32°C in the first days to 28°C by the end.

A typical September day in Semnan reaches about 30°C in the afternoon and slips back to 18°C overnight — a 12°C spread between the day's warmth and the night's chill. On most days the high lands between 26°C and 33°C. Set against its neighbours, September runs about 4°C cooler than August and about 7°C warmer than October.

	1	2	3	4	5	6	7	8	9	10	11	12	13	14	15	16	17	18	19	20	21	22	23	24	25	26	27	28	29	30
Avg high (°C)	33	33	32	32	32	32	32	32	32	31	31	31	31	31	30	30	30	30	30	29	29	29	29	29	28	28	28	28	27	27
Avg low (°C)	21	21	20	20	20	20	20	20	20	19	19	19	19	19	19	18	18	18	18	18	17	17	17	17	17	16	16	16	16	15

	Avg high (°C)	Avg low (°C)
1	33	21
2	33	21
3	32	20
4	32	20
5	32	20
6	32	20
7	32	20
8	32	20
9	32	20
10	31	19
11	31	19
12	31	19
13	31	19
14	31	19
15	30	19
16	30	18
17	30	18
18	30	18
19	30	18
20	29	18
21	29	17
22	29	17
23	29	17
24	29	17
25	28	17
26	28	16
27	28	16
28	28	16
29	27	16
30	27	15

How September really feels in Semnan

Once humidity and wind are folded in, September averages 6 days that feel above 32°C and 0 that feel at or below 0°C — the comfort signal a plain temperature reading hides.

Days feeling ≥ 32°C

heat index over the day's high

Days feeling ≤ 0°C

wind chill below the day's low

The story in September is heat — humidity pushes the afternoon "feels like" well above the raw temperature.

Semnan weather by month

How September compares with the rest of the year at a glance. September is the 4th-warmest and 9th-wettest month here — the current month is highlighted below.

Month	High / Low (°C)	Rainfall (mm)	Wet days	Snow days	Daylight (hours)	Travel score
Jan	8° / -0°	12	3.2	1.7	9.9	1.6
Feb	10° / 1°	14	2.9	1.4	10.7	2.9
Mar	16° / 6°	18	3.9	0.9	11.7	5.7
Apr	22° / 11°	13	2.7	0.1	12.9	8.0
May	28° / 17°	5	1.3	0	13.9	7.6
Jun	33° / 21°	1	0.3	0	14.4	4.5
Jul	36° / 24°	1	0.3	0	14.2	2.9
Aug	35° / 23°	1	0.3	0	13.3	3.8
Sep	30° / 18°	2	0.5	0	12.2	6.8
Oct	23° / 12°	5	1.1	0	11.1	8.8
Nov	15° / 6°	11	3	0.2	10.1	5.4
Dec	9° / 1°	10	3.1	0.9	9.6	2.3

Cloud cover in September

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 94% of the time in September.

Beyond those clear spells, partly cloudy skies cover about 5% of September, with mostly cloudy or overcast conditions the remaining 2%. Skies tend to cloud over as the month goes on.

	1	2	3	4	5	6	7	8	9	10	11	12	13	14	15	16	17	18	19	20	21	22	23	24	25	26	27	28	29	30
Clearer (%)	100	100	100	100	100	100	100	100	99	99	99	99	99	99	99	99	98	98	98	98	98	98	98	98	96	96	96	96	96	96
Cloudier (%)	0	0	0	0	0	0	0	0	1	1	1	1	1	1	1	1	2	2	2	2	2	2	2	2	4	4	4	4	4	4

	Clearer (%)	Cloudier (%)
1	100	0
2	100	0
3	100	0
4	100	0
5	100	0
6	100	0
7	100	0
8	100	0
9	99	1
10	99	1
11	99	1
12	99	1
13	99	1
14	99	1
15	99	1
16	99	1
17	98	2
18	98	2
19	98	2
20	98	2
21	98	2
22	98	2
23	98	2
24	98	2
25	96	4
26	96	4
27	96	4
28	96	4
29	96	4
30	96	4

Chance of precipitation in September

Any precipitation

Semnan gets around 2 mm of rain over 0.5 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 2% and peaks near 2% on the wettest days.

	1	2	3	4	5	6	7	8	9	10	11	12	13	14	15	16	17	18	19	20	21	22	23	24	25	26	27	28	29	30
Rain chance (%)	1	1	1	1	1	1	1	1	1	1	1	2	2	2	2	2	2	2	2	2	2	2	2	2	2	2	2	2	2	2

	Rain chance (%)
1	1
2	1
3	1
4	1
5	1
6	1
7	1
8	1
9	1
10	1
11	1
12	2
13	2
14	2
15	2
16	2
17	2
18	2
19	2
20	2
21	2
22	2
23	2
24	2
25	2
26	2
27	2
28	2
29	2
30	2

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 99% of days. It rarely turns muggy — the humid and sticky bands barely register.

	1	2	3	4	5	6	7	8	9	10	11	12	13	14	15	16	17	18	19	20	21	22	23	24	25	26	27	28	29	30
Dry (%)	96	97	97	98	98	99	99	99	99	99	99	99	100	100	100	100	100	100	100	100	100	100	100	100	100	100	100	100	100	100
Comfortable (%)	4	3	3	2	2	1	1	1	1	1	1	1	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0

	Dry (%)	Comfortable (%)
1	96	4
2	97	3
3	97	3
4	98	2
5	98	2
6	99	1
7	99	1
8	99	1
9	99	1
10	99	1
11	99	1
12	99	1
13	100	0
14	100	0
15	100	0
16	100	0
17	100	0
18	100	0
19	100	0
20	100	0
21	100	0
22	100	0
23	100	0
24	100	0
25	100	0
26	100	0
27	100	0
28	100	0
29	100	0
30	100	0

Wind in September

Winds average 11 km/h in September.

Across September, daily wind ranges from about 10 km/h on the calmest days to 11 km/h at its breeziest. It stays fairly steady from day to day.

	1	2	3	4	5	6	7	8	9	10	11	12	13	14	15	16	17	18	19	20	21	22	23	24	25	26	27	28	29	30
Wind speed (km/h)	11	11	11	11	11	11	11	11	11	11	11	11	11	11	11	11	11	11	11	11	10	10	10	10	10	10	10	10	10	10
Feels	calm	calm	calm	calm	calm	calm	calm	calm	calm	calm	calm	calm	calm	calm	calm	calm	calm	calm	calm	calm	calm	calm	calm	calm	calm	calm	calm	calm	calm	calm

	Wind speed (km/h)	Feels
1	11	calm
2	11	calm
3	11	calm
4	11	calm
5	11	calm
6	11	calm
7	11	calm
8	11	calm
9	11	calm
10	11	calm
11	11	calm
12	11	calm
13	11	calm
14	11	calm
15	11	calm
16	11	calm
17	11	calm
18	11	calm
19	11	calm
20	11	calm
21	10	calm
22	10	calm
23	10	calm
24	10	calm
25	10	calm
26	10	calm
27	10	calm
28	10	calm
29	10	calm
30	10	calm

Sunrise & sunset in September

DaylightNight

Daylight runs from about 12 h 48 min at the start of September to 11 h 42 min by month's end. The lit band spans sunrise to sunset each day.

Days shrink by about 66 minutes over September. Sunrise moves from 5:32 AM to 5:55 AM, and sunset from 6:20 PM to 5:36 PM.

	1	2	3	4	5	6	7	8	9	10	11	12	13	14	15	16	17	18	19	20	21	22	23	24	25	26	27	28	29	30
Daylight (h)	12.8	12.8	12.7	12.7	12.6	12.6	12.6	12.5	12.5	12.5	12.4	12.4	12.3	12.3	12.3	12.2	12.2	12.1	12.1	12.1	12.0	12.0	12.0	11.9	11.9	11.8	11.8	11.8	11.7	11.7
Sunrise (AM)	5:32	5:33	5:34	5:35	5:36	5:36	5:37	5:38	5:39	5:39	5:40	5:41	5:42	5:43	5:43	5:44	5:45	5:46	5:46	5:47	5:48	5:49	5:50	5:50	5:51	5:52	5:53	5:54	5:54	5:55
Sunset (PM)	6:20	6:18	6:17	6:15	6:14	6:12	6:11	6:09	6:08	6:06	6:05	6:03	6:02	6:00	5:59	5:57	5:56	5:54	5:53	5:51	5:50	5:48	5:47	5:45	5:44	5:42	5:41	5:39	5:38	5:36

	Daylight (h)	Sunrise (AM)	Sunset (PM)
1	12.8	5:32	6:20
2	12.8	5:33	6:18
3	12.7	5:34	6:17
4	12.7	5:35	6:15
5	12.6	5:36	6:14
6	12.6	5:36	6:12
7	12.6	5:37	6:11
8	12.5	5:38	6:09
9	12.5	5:39	6:08
10	12.5	5:39	6:06
11	12.4	5:40	6:05
12	12.4	5:41	6:03
13	12.3	5:42	6:02
14	12.3	5:43	6:00
15	12.3	5:43	5:59
16	12.2	5:44	5:57
17	12.2	5:45	5:56
18	12.1	5:46	5:54
19	12.1	5:46	5:53
20	12.1	5:47	5:51
21	12.0	5:48	5:50
22	12.0	5:49	5:48
23	12.0	5:50	5:47
24	11.9	5:50	5:45
25	11.9	5:51	5:44
26	11.8	5:52	5:42
27	11.8	5:53	5:41
28	11.8	5:54	5:39
29	11.7	5:54	5:38
30	11.7	5:55	5:36

Solar energy in September

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in September, about 5.89 kWh/m².

For context, solar energy here swings from a low near 2.8 kWh/m² to a high of 7.71 kWh/m² in June across the year — September's 5.89 kWh/m² falls in the middle.

	1	2	3	4	5	6	7	8	9	10	11	12	13	14	15	16	17	18	19	20	21	22	23	24	25	26	27	28	29	30
Solar energy (kWh/m²)	6.5	6.5	6.4	6.4	6.3	6.3	6.3	6.2	6.2	6.1	6.1	6.0	6.0	5.9	5.9	5.8	5.8	5.8	5.7	5.7	5.6	5.6	5.6	5.5	5.5	5.4	5.4	5.4	5.3	5.3
Level	Intense	Intense	Intense	Intense	Intense	Intense	Intense	Intense	Intense	Intense	Intense	Intense	Bright	Bright	Bright	Bright	Bright	Bright	Bright	Bright	Bright	Bright	Bright	Bright	Bright	Bright	Bright	Bright	Bright	Bright

	Solar energy (kWh/m²)	Level
1	6.5	Intense
2	6.5	Intense
3	6.4	Intense
4	6.4	Intense
5	6.3	Intense
6	6.3	Intense
7	6.3	Intense
8	6.2	Intense
9	6.2	Intense
10	6.1	Intense
11	6.1	Intense
12	6.0	Intense
13	6.0	Bright
14	5.9	Bright
15	5.9	Bright
16	5.8	Bright
17	5.8	Bright
18	5.8	Bright
19	5.7	Bright
20	5.7	Bright
21	5.6	Bright
22	5.6	Bright
23	5.6	Bright
24	5.5	Bright
25	5.5	Bright
26	5.4	Bright
27	5.4	Bright
28	5.4	Bright
29	5.3	Bright
30	5.3	Bright

Planning a trip in September

Is September a good time to visit Semnan?

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

6.8

Sightseeing

4th-best month of the year

9.0

Beach & pool

1st-best month of the year

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

What to pack for Semnan in September

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

In September, Semnan sees daytime highs around 30°C and nights near 18°C. Pack light clothes. Worth having: sun protection.

light clothessun protection

UV index in Semnan in September

LowModerateHighVery highExtreme

Clear-sky midday UV in September peaks around 8 (very high — sun protection essential). The full-year curve, shaded by WHO exposure level, is below.

Under clear skies, the midday UV index in Semnan peaks around July 19 at about 11 (extreme) — sunscreen, a hat and midday shade are essential. It bottoms out near January 10 at about 3 (moderate).

The index reaches 3 or more — the level where the WHO recommends sun protection — in 11 months of the year.

	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
UV index (midday)	3	5	5	8	10	10	11	10	8	6	4	3
Level	Moderate	High	Moderate	Very high	Very high	Very high	Extreme	Extreme	Very high	High	Moderate	Moderate

	UV index (midday)	Level
Jan	3	Moderate
Feb	5	High
Mar	5	Moderate
Apr	8	Very high
May	10	Very high
Jun	10	Very high
Jul	11	Extreme
Aug	10	Extreme
Sep	8	Very high
Oct	6	High
Nov	4	Moderate
Dec	3	Moderate

Air quality in Semnan 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 Semnan is worst in December — around 46 µg/m³ PM2.5 (poor), about 2.1× the cleanest month (August, 22 µg/m³).

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

	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
PM2.5 (µg/m³)	43	41	38	40	34	23	23	22	28	32	39	46
Level	Poor	Poor	Poor	Poor	Moderate	Moderate	Moderate	Moderate	Moderate	Moderate	Poor	Poor

	PM2.5 (µg/m³)	Level
Jan	43	Poor
Feb	41	Poor
Mar	38	Poor
Apr	40	Poor
May	34	Moderate
Jun	23	Moderate
Jul	23	Moderate
Aug	22	Moderate
Sep	28	Moderate
Oct	32	Moderate
Nov	39	Poor
Dec	46	Poor

Location & terrain

Where is Semnan?

Semnan sits at 35.6°N, 53.4°E, 1,148 m above sea level, in Iran. The nearest listed city is Mahdishahr, 15 km away.

Topography around Semnan

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

Within 3 km, the terrain around Semnan has only modest variations in elevation — a maximum elevation change of 144 m around an average of 1,149 m above sea level; within 16 km, very significant variations in elevation — a maximum elevation change of 1,254 m; within 80 km, extreme variations in elevation — a maximum elevation change of 3,375 m.

The land around Semnan is covered by artificial surfaces (59%) and bare terrain (20%) within 3 km, bare terrain (84%) within 16 km, and bare terrain (67%) and grassland (22%) within 80 km.

3 km

144 m

artificial surfaces 59%

16 km

1,254 m

bare terrain 84%

80 km

3,375 m

bare terrain 67%

treesgrasslandcroplandartificial surfacesbare terrain

← August Semnan year-round climate October →Best places to visit in September

September weather nearby: Mahdishahr 15 km · Fīrūzkūh 60 km · Zīr Āb 77 km · Garmsār 103 km · Īstgāh-e Rāh Āhan-e Garmsār 105 km · Dāmghān 108 km · Qā’em Shahr 110 km · Sari 114 km

Iran travel facts

Travel advisory: Level 4; Do Not Travel
Power plugs: Type C / F; 220 V · 50 Hz
Prices: ≈ 352% of US; price level, 2025
GDP per capita: $3,924; 2025
Happiness: 5.2 / 10; World Happiness, 2025
Safe drinking water: 94%; of population, 2024
Homicide rate: 2.4; per 100k, 2014
Road deaths: 21.5; per 100k/yr, 2019
Income group: Upper middle; World Bank
English: Low; EF EPI 492
Religion

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 Semnan (35.5769°, 53.392°, elevation 1,148 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).

	Avg high (°C)	Avg low (°C)
1	33	21
2	33	21
3	32	20
4	32	20
5	32	20
6	32	20
7	32	20
8	32	20
9	32	20
10	31	19
11	31	19
12	31	19
13	31	19
14	31	19
15	30	19
16	30	18
17	30	18
18	30	18
19	30	18
20	29	18
21	29	17
22	29	17
23	29	17
24	29	17
25	28	17
26	28	16
27	28	16
28	28	16
29	27	16
30	27	15

	Clearer (%)	Cloudier (%)
1	100	0
2	100	0
3	100	0
4	100	0
5	100	0
6	100	0
7	100	0
8	100	0
9	99	1
10	99	1
11	99	1
12	99	1
13	99	1
14	99	1
15	99	1
16	99	1
17	98	2
18	98	2
19	98	2
20	98	2
21	98	2
22	98	2
23	98	2
24	98	2
25	96	4
26	96	4
27	96	4
28	96	4
29	96	4
30	96	4

	Rain chance (%)
1	1
2	1
3	1
4	1
5	1
6	1
7	1
8	1
9	1
10	1
11	1
12	2
13	2
14	2
15	2
16	2
17	2
18	2
19	2
20	2
21	2
22	2
23	2
24	2
25	2
26	2
27	2
28	2
29	2
30	2

	Dry (%)	Comfortable (%)
1	96	4
2	97	3
3	97	3
4	98	2
5	98	2
6	99	1
7	99	1
8	99	1
9	99	1
10	99	1
11	99	1
12	99	1
13	100	0
14	100	0
15	100	0
16	100	0
17	100	0
18	100	0
19	100	0
20	100	0
21	100	0
22	100	0
23	100	0
24	100	0
25	100	0
26	100	0
27	100	0
28	100	0
29	100	0
30	100	0

	Avg high (°C)	Avg low (°C)
1	33	21
2	33	21
3	32	20
4	32	20
5	32	20
6	32	20
7	32	20
8	32	20
9	32	20
10	31	19
11	31	19
12	31	19
13	31	19
14	31	19
15	30	19
16	30	18
17	30	18
18	30	18
19	30	18
20	29	18
21	29	17
22	29	17
23	29	17
24	29	17
25	28	17
26	28	16
27	28	16
28	28	16
29	27	16
30	27	15

	Clearer (%)	Cloudier (%)
1	100	0
2	100	0
3	100	0
4	100	0
5	100	0
6	100	0
7	100	0
8	100	0
9	99	1
10	99	1
11	99	1
12	99	1
13	99	1
14	99	1
15	99	1
16	99	1
17	98	2
18	98	2
19	98	2
20	98	2
21	98	2
22	98	2
23	98	2
24	98	2
25	96	4
26	96	4
27	96	4
28	96	4
29	96	4
30	96	4

	Rain chance (%)
1	1
2	1
3	1
4	1
5	1
6	1
7	1
8	1
9	1
10	1
11	1
12	2
13	2
14	2
15	2
16	2
17	2
18	2
19	2
20	2
21	2
22	2
23	2
24	2
25	2
26	2
27	2
28	2
29	2
30	2

	Dry (%)	Comfortable (%)
1	96	4
2	97	3
3	97	3
4	98	2
5	98	2
6	99	1
7	99	1
8	99	1
9	99	1
10	99	1
11	99	1
12	99	1
13	100	0
14	100	0
15	100	0
16	100	0
17	100	0
18	100	0
19	100	0
20	100	0
21	100	0
22	100	0
23	100	0
24	100	0
25	100	0
26	100	0
27	100	0
28	100	0
29	100	0
30	100	0

	Avg high (°C)	Avg low (°C)
1	33	21
2	33	21
3	32	20
4	32	20
5	32	20
6	32	20
7	32	20
8	32	20
9	32	20
10	31	19
11	31	19
12	31	19
13	31	19
14	31	19
15	30	19
16	30	18
17	30	18
18	30	18
19	30	18
20	29	18
21	29	17
22	29	17
23	29	17
24	29	17
25	28	17
26	28	16
27	28	16
28	28	16
29	27	16
30	27	15

	Clearer (%)	Cloudier (%)
1	100	0
2	100	0
3	100	0
4	100	0
5	100	0
6	100	0
7	100	0
8	100	0
9	99	1
10	99	1
11	99	1
12	99	1
13	99	1
14	99	1
15	99	1
16	99	1
17	98	2
18	98	2
19	98	2
20	98	2
21	98	2
22	98	2
23	98	2
24	98	2
25	96	4
26	96	4
27	96	4
28	96	4
29	96	4
30	96	4

	Rain chance (%)
1	1
2	1
3	1
4	1
5	1
6	1
7	1
8	1
9	1
10	1
11	1
12	2
13	2
14	2
15	2
16	2
17	2
18	2
19	2
20	2
21	2
22	2
23	2
24	2
25	2
26	2
27	2
28	2
29	2
30	2

	Dry (%)	Comfortable (%)
1	96	4
2	97	3
3	97	3
4	98	2
5	98	2
6	99	1
7	99	1
8	99	1
9	99	1
10	99	1
11	99	1
12	99	1
13	100	0
14	100	0
15	100	0
16	100	0
17	100	0
18	100	0
19	100	0
20	100	0
21	100	0
22	100	0
23	100	0
24	100	0
25	100	0
26	100	0
27	100	0
28	100	0
29	100	0
30	100	0