Seongnam-si climate

Name: Seongnam-si
Address: KR

Seongnam-si is warmest in August, with average highs of 28 °C, and coldest in January, when nights average -6.6 °C. July is the wettest month (339 mm) and January the driest (20 mm). Figures are 1991–2020 climate normals.

Across a full year Seongnam-si averages 1,294 mm of rain, 95 days above 25 °C and 113 days below freezing.

South Korea · population 914,832 · 1991–2020 normals

Temperature below 0 °C to above 30 °C Rain band height is that month’s share of the wettest month

Warmest month August 28 °C
Coldest month January -6.6 °C
Driest month January 20 mm
Wettest month July 339 mm
Least cloud December 42 % cloud
Hottest on record August 37 °C
Coldest on record January -23 °C

What to expectSeongnam-si through the year

Seongnam-si has a clear annual cycle: average daily highs run from 1.6 °C in January to 28 °C in August, a swing of 28 °C in mean temperature across the year.

Counted across a normal year, 95 days a year reach 25 °C, 18 of them reach 30 °C, 113 nights drop below freezing. The warmest reading in the 1991–2020 record is 37 °C, in August.

Rain is strongly seasonal. July averages 339 mm against 20 mm in January — 17 times as much. Planning around the dry months matters more here than planning around temperature.

Month by month

Month	Avg high	Rainfall	Cloud
January	1.6 °C	20 mm	44 %
February	4.5 °C	29 mm	46 %
March	9.9 °C	41 mm	50 %
April	16.5 °C	77 mm	52 %
May	21.9 °C	102 mm	57 %
June	26.2 °C	140 mm	66 %
July	27.9 °C	339 mm	76 %
August	28.5 °C	281 mm	68 %
September	24.5 °C	133 mm	59 %
October	18.5 °C	57 mm	46 %
November	10.6 °C	49 mm	46 %
December	3.5 °C	25 mm	42 %

Temperature month by month

Month	Avg high	Avg low	Mean	Record high	Record low	Days above 25 °C	Days above 30 °C	Days below 0 °C
January	1.6 °C	-6.6 °C	-2.7 °C	13.7 °C	-22.8 °C	0	0	30
February	4.5 °C	-4.4 °C	-0.4 °C	17.6 °C	-20.1 °C	0	0	26
March	9.9 °C	-0.0 °C	4.5 °C	20.9 °C	-11.4 °C	0	0	17
April	16.5 °C	5.8 °C	10.8 °C	28.7 °C	-2.5 °C	0	0	2
May	21.9 °C	11.7 °C	16.5 °C	31.5 °C	4.7 °C	6	0	0
June	26.2 °C	17.2 °C	21.4 °C	34.0 °C	10.4 °C	21	2	0
July	27.9 °C	21.5 °C	24.3 °C	35.5 °C	14.4 °C	27	6	0
August	28.5 °C	21.9 °C	24.8 °C	36.9 °C	13.3 °C	28	9	0
September	24.5 °C	16.4 °C	20.2 °C	31.8 °C	7.1 °C	13	0	0
October	18.5 °C	9.2 °C	13.6 °C	27.1 °C	-2.1 °C	1	0	0
November	10.6 °C	2.0 °C	6.1 °C	23.8 °C	-12.5 °C	0	0	11
December	3.5 °C	-4.5 °C	-0.8 °C	14.8 °C	-18.0 °C	0	0	28

Rain, sun and wind month by month

Month	Rainfall	Wet days	Daylight	Cloud cover	Humidity	Wind
January	20 mm	4	9.9 h/day	44 %	60 %	14 km/h
February	29 mm	4	11 h/day	46 %	61 %	15 km/h
March	41 mm	6	12 h/day	50 %	66 %	16 km/h
April	77 mm	7	13 h/day	52 %	67 %	16 km/h
May	102 mm	8	14 h/day	57 %	71 %	15 km/h
June	140 mm	9	15 h/day	66 %	75 %	13 km/h
July	339 mm	17	15 h/day	76 %	84 %	13 km/h
August	281 mm	16	14 h/day	68 %	83 %	12 km/h
September	133 mm	8	12 h/day	59 %	77 %	11 km/h
October	57 mm	5	11 h/day	46 %	72 %	12 km/h
November	49 mm	7	10 h/day	46 %	70 %	13 km/h
December	25 mm	5	9.6 h/day	42 %	64 %	14 km/h

How Seongnam-si compares

The same four figures for nearby destinations, so the numbers above have something to be read against. Summer high is the warmest month's average high; winter low is the coldest month's average low.

Destination	Summer high	Winter low	Rain per year	Days above 25 °C
Seongnam-si	28 °C	-6.6 °C	1,294 mm	95
Gunpo · South Korea	28 °C	-6.1 °C	1,139 mm	85
Anyang-si · South Korea	28 °C	-6.1 °C	1,209 mm	84
Suwon · South Korea	28 °C	-6.2 °C	1,146 mm	93
Seoul · South Korea	29 °C	-7.1 °C	1,206 mm	97
Bucheon-si · South Korea	28 °C	-6.4 °C	1,153 mm	83
Icheon-si · South Korea	29 °C	-6.5 °C	1,232 mm	103

Planning a trip? See the best time to visit Seongnam-si.

QuestionsCommon questions about Seongnam-si’s climate

When is the best time to visit Seongnam-si?

That depends on what you want, so the honest answer is a comparison rather than a single month. May, June, September sit closest to 20 °C on average, August is the warmest month and January the driest. The month-by-month table above has the full picture.

How hot does Seongnam-si get?

In August, the warmest month, daily highs average 28 °C. About 18 days a year pass 30 °C. The highest value in the 1991–2020 record is 37 °C.

How cold does it get in winter?

Nights average -6.6 °C in January, the coldest month. A normal year has 113 nights below freezing.

Which month is wettest in Seongnam-si?

July, averaging 339 mm over 17 days with rain. The driest month is January with 20 mm. The year as a whole averages 1,294 mm.

Are these figures a forecast?

No. They are 1991–2020 climate normals: the average of thirty years, which describes what a month is usually like in Seongnam-si rather than what any particular week will bring. Individual years can differ substantially from the normal.

Data sources and method

ERA5 / ERA5-Land reanalysis — Copernicus Climate Change Service (C3S), ECMWF. Copernicus Licence
Open-Meteo — Open-Meteo.com. CC BY 4.0
NOAA OISST v2.1 — NOAA Physical Sciences Laboratory. Public domain
GeoNames — GeoNames.org. CC BY 4.0

Normal period: 1991–2020
Dataset version: era5-1991-2020-scores1.1
Last processed: 1 August 2026

Measured values come from ERA5 reanalysis and are reproduced unchanged. Calculated by us: monthly rankings, daylight hours, beach and comfort scores. Full formulas are on the methodology page.

Contains modified Copernicus Climate Change Service information 2026. Neither the European Commission nor ECMWF is responsible for any use that may be made of the Copernicus information or data it contains.