Mirissa weather in September

In September, Mirissa sees average daytime highs of 29°C and overnight lows near 25°C, with 202 mm of rain across 26.3 wet days and about 12 hours of daylight. It is the 10th-warmest and 4th-wettest month of the year here.

Day-to-day highs hold fairly steady near 29°C through the month. The sky is clear or mostly clear about 4% of the time in September, and the air most often feels oppressive.

Daylight stretches from about 12 h 06 min at the start of September to 12 hours by month's end. Set against the rest of the year, September is Mirissa's 9th-clearest and 4th-windiest month. For the whole year in context, see Mirissa's year-round climate.

Daytime high
29°
10th warmest
Overnight low
25°
7th coldest
Rainfall
202 mm
26.3 wet days
Daylight
12 hours
6:02 AM – 6:03 PM
Cloud cover
80%
9th clearest
Wind
17 km/h
4th windiest
Solar energy
5.53 kWh/m²
Travel score
3.4
out of 10

Mirissa is place in Southern Province, Sri Lanka.

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 29°C through the month.

A typical September day in Mirissa reaches about 29°C in the afternoon and slips back to 25°C overnight — a 4°C spread between the day's warmth and the night's chill. On most days the high lands between 27°C and 30°C. Set against its neighbours, September runs on par with August and on par with October.

20°23°25°28°30°151015202530
Avg high (°C)Avg low (°C)
12825
22825
32825
42825
52825
62825
72825
82825
92825
102825
112825
122825
132825
142825
152825
162825
172825
182925
192925
202925
212925
222925
232925
242925
252925
262925
272925
282925
292925
302925

How September really feels in Mirissa

Once humidity and wind are folded in, September averages 30 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
30
heat index over the day's high
Days feeling ≤ C
0
wind chill below the day's low

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

Mirissa weather by month

How September compares with the rest of the year at a glance. September is the 10th-warmest and 4th-wettest month here — the current month is highlighted below.

MonthHigh / Low (°C)Rainfall (mm)Wet daysDaylight (hours)Travel score
Jan29° / 24°9914.611.74.7
Feb30° / 24°8413.111.84.4
Mar31° / 25°10318.7123.8
Apr30° / 25°18925.712.13.1
May29° / 26°22128.112.33.0
Jun29° / 25°18726.812.33.2
Jul28° / 25°15326.512.33.5
Aug28° / 25°15826.812.23.5
Sep29° / 25°20226.3123.4
Oct29° / 24°25126.511.93.4
Nov29° / 24°29825.111.73.4
Dec29° / 24°20021.411.74.0

Cloud cover in September

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 4% of the time in September.

Beyond those clear spells, partly cloudy skies cover about 15% of September, with mostly cloudy or overcast conditions the remaining 81%.

0%25%50%75%100%151015202530
Clearer (%)Cloudier (%)
11783
21783
31882
41882
51882
61981
71981
81882
91981
101981
111981
121981
131981
141882
151882
161981
171882
181882
191882
201882
211882
221882
231783
241981
251981
261981
271981
282080
292080
302278

Chance of precipitation in September

Any precipitation

Mirissa gets around 202 mm of rain over 26.3 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 87% and peaks near 89% on the wettest days.

0%20%40%60%80%100%151015202530
Rain chance (%)
185
286
386
486
586
687
787
887
988
1088
1188
1288
1388
1488
1588
1689
1789
1889
1989
2089
2188
2288
2388
2488
2587
2687
2787
2886
2986
3085

Humidity in September

DryComfortableHumidMuggyOppressiveMiserable

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

By dew point, September lands in the oppressive band about 51% of days. Sticky, muggy-or-worse air turns up on roughly 100% of them.

0%25%50%75%100%151015202530
Oppressive (%)Miserable (%)
15248
25248
35248
45248
55248
65149
75149
85149
95050
105050
115050
124951
134951
144852
154852
164852
174852
184852
194951
204951
214951
225050
235050
245149
255149
265248
275347
285347
295347
305446

Wind in September

Winds average 17 km/h in September.

Across September, daily wind ranges from about 16 km/h on the calmest days to 18 km/h at its breeziest. It stays fairly steady from day to day.

05101520151015202530
Wind speed (km/h)Feels
118light breeze
218light breeze
318light breeze
418light breeze
517light breeze
617light breeze
717light breeze
817light breeze
917light breeze
1017light breeze
1117light breeze
1217light breeze
1317light breeze
1417light breeze
1517light breeze
1617light breeze
1717light breeze
1817light breeze
1917light breeze
2017light breeze
2117light breeze
2217light breeze
2316light breeze
2416light breeze
2516light breeze
2616light breeze
2716light breeze
2816light breeze
2916light breeze
3016light breeze

Sunrise & sunset in September

DaylightNight

Daylight runs from about 12 h 06 min at the start of September to 12 hours by month's end. The lit band spans sunrise to sunset each day.

Days shrink by about 6 minutes over September. Sunrise moves from 6:04 AM to 5:59 AM, and sunset from 6:11 PM to 5:56 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202530
Daylight (h)Sunrise (AM)Sunset (PM)
112.16:046:11
212.16:046:11
312.16:046:10
412.16:046:10
512.16:046:09
612.16:046:09
712.16:036:08
812.16:036:08
912.16:036:07
1012.16:036:07
1112.16:036:06
1212.16:026:06
1312.06:026:05
1412.06:026:05
1512.06:026:04
1612.06:026:03
1712.06:016:03
1812.06:016:02
1912.06:016:02
2012.06:016:01
2112.06:016:01
2212.06:006:00
2312.06:006:00
2412.06:005:59
2512.06:005:59
2612.06:005:58
2712.05:595:58
2812.05:595:57
2912.05:595:57
3012.05:595:56

Solar energy in September

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in September, about 5.53 kWh/m².

For context, solar energy here swings from a low near 4.83 kWh/m² to a high of 6.46 kWh/m² in March across the year — September's 5.53 kWh/m² falls in the middle.

0246151015202530
Solar energy (kWh/m²)Level
15.6Bright
25.6Bright
35.6Bright
45.6Bright
55.6Bright
65.6Bright
75.6Bright
85.6Bright
95.6Bright
105.6Bright
115.6Bright
125.6Bright
135.6Bright
145.6Bright
155.6Bright
165.6Bright
175.5Bright
185.5Bright
195.5Bright
205.5Bright
215.5Bright
225.5Bright
235.5Bright
245.5Bright
255.5Bright
265.5Bright
275.5Bright
285.5Bright
295.5Bright
305.5Bright
Planning a trip in September

Hazard calendar for Mirissa

In seasonPeak

In September, Mirissa sits inside its cyclone season. The full year is below, with each hazard's peak months called out.

Mirissa sits in the North Indian Ocean cyclone zone; the season peaks May and October–November.

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

Is September a good time to visit Mirissa?

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

3.4
Sightseeing
7th-best month of the year
4.1
Beach & pool
10th-best month of the year

September is a weaker month for outdoor sightseeing in Mirissa.

What to pack for Mirissa in September

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

In September, Mirissa sees daytime highs around 29°C and nights near 25°C. Pack light clothes and rain gear. Worth having: sun protection. About 26 days see rain.

light clothesrain gearsun protection

Sea temperature near Mirissa in September

The nearest coast averages about 28°C 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 April at about 30°C and coldest in July near 28°C.

The water stays above 20°C all year — warm enough for a swim any month.

26°28°30°JanFebMarAprMayJunJulAugSepOctNovDecwarmtropicalcomfortable to swim
Sea temperature (°C)Comfort
Jan28Warm
Feb28Tropical
Mar29Tropical
Apr30Tropical
May29Tropical
Jun28Tropical
Jul28Warm
Aug28Warm
Sep28Warm
Oct28Tropical
Nov29Tropical
Dec28Tropical

UV index in Mirissa in September

LowModerateHighVery highExtreme

Clear-sky midday UV in September peaks around 13 (very high — sun protection essential). The full-year curve, shaded by WHO exposure level, is below.

Under clear skies, the midday UV index in Mirissa peaks around April 17 at about 14 (extreme) — sunscreen, a hat and midday shade are essential. It bottoms out near January 11 at about 9 (very high).

The index reaches 3 or more — the level where the WHO recommends sun protection — every month of the year.

025710JanFebMarAprMayJunJulAugSepOctNovDecExtremeApr 17UV 14Jan 11UV 9
UV index (midday)Level
Jan9Very high
Feb14Extreme
Mar12Extreme
Apr14Extreme
May13Extreme
Jun11Extreme
Jul11Extreme
Aug13Extreme
Sep13Extreme
Oct13Extreme
Nov11Extreme
Dec10Very high

Air quality in Mirissa 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 Mirissa is worst in January — around 35 µg/m³ PM2.5 (moderate), about 2.1× the cleanest month (September, 16 µg/m³).

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

010203040JanFebMarAprMayJunJulAugSepOctNovDecModerateJan 1834 µg/m³Sep 1316 µg/m³
PM2.5 (µg/m³)Level
Jan35Moderate
Feb31Moderate
Mar25Moderate
Apr21Moderate
May20Moderate
Jun18Moderate
Jul17Moderate
Aug17Moderate
Sep16Moderate
Oct18Moderate
Nov25Moderate
Dec30Moderate
Location & terrain

Where is Mirissa?

Mirissa sits at 5.9°N, 80.5°E, 0 m above sea level, in Sri Lanka. The nearest listed city is Weligama, 4.0 km away.

UnawatunaGalleBeliattaAmbalangodaAmbalantota

Topography around Mirissa

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

Within 3 km, the terrain around Mirissa has only modest variations in elevation — a maximum elevation change of 57 m around an average of 5 m above sea level; within 16 km, significant variations in elevation — a maximum elevation change of 291 m; within 80 km, very significant variations in elevation — a maximum elevation change of 1,507 m.

The land around Mirissa is covered by water (60%) and trees (34%) within 3 km, water (54%) and trees (37%) within 16 km, and trees (52%) and water (44%) within 80 km.

3 km
57 m
16 km
291 m
80 km
1,507 m
treesgrasslandcroplandartificial surfaceswaterwetland
September weather nearby: Weligama 4.0 km · Matara 9.0 km · Devinuwara 15 km · Unawatuna 24 km · Galle 30 km · Beliatta 32 km · Ambalangoda 55 km · Ambalantota 65 km

Sri Lanka travel facts

Travel advisory
Level 2
Exercise Increased Caution
Power plugs
Type D / G / M
230 V · 50 Hz
Prices
≈ 27% of US
price level, 2025
GDP per capita
$5,002
2025
Happiness
4.0 / 10
World Happiness, 2025
Safe drinking water
47%
of population, 2024
Homicide rate
3.3
per 100k, 2019
Road deaths
19.7
per 100k/yr, 2019
Income group
Upper middle
World Bank
English
Low
EF EPI 486
Religion
Buddhist 70%Hindu 13%Muslim 10%Roman Catholic 6%

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 Mirissa (5.9466°, 80.4583°, elevation 0 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. Tropical-cyclone seasons are the published climatological basin seasons (NOAA National Hurricane Center / regional warning centres). 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).