Seongnam-si weather history
Live conditions, the day's high and low compared with the long-term normal, monthly climate averages, all-time records and the city's warming trend since 1940 — all on one page for Seongnam-si, South Korea.
Today
28°/13°
Normal for this date 25° / 15°
Much warmer+3.6°CHow it’s changed
Right now
What it's doing today vs the historical normal for this date.
Right now
15.1°
28°13°
23°18°26°16°28°14°
25°14°27°16°29°14°On this date — June 5
Warmer than usual · 3.6°C above the normal high
- Record high: 31.1° · 2016
- Record low: 9.9° · 1962
- One year ago: 26.4°
Every June 5 in history — coldest to hottest
Dots show daily highs (top) and lows (bottom) for each June 5 on record (n = 86). Outlined dots are today's forecast.
Next 24 hours
16°15°15°14°
14°13°13°15°18°20°23°25°26°27°28°28°28°Last 30 days
18 of the last 24 days were warmer than the historical normal for that date. Average difference: +2.2°C.
Each bar is one day, from morning low to afternoon high. Warm-colored bars are days whose mean ran above normal; cool bars ran below. The dot inside the bar is the daily mean. The shaded band is the typical 10–90% range expected for that date. Normal = the day's mean temperature averaged across every year of record (1940–2026) for that calendar date.
Climate
What a typical year looks like — built from the full record.Climate overview
The warmest month of the year in Seongnam-si is August, with a daily mean around 25.0°C and typical afternoon highs of 28.9°C. The coolest is January, when daily means drop to roughly -4.2°C and overnight lows hover around -9.0°C. Between the two extremes the climate moves through a fairly predictable seasonal cycle that you can see in the monthly chart below.
Total annual precipitation in Seongnam-si averages about 1356 mm. The wettest month is usually July with around 347 mm of rain, while January is the driest at roughly 26 mm. The split between wet and dry seasons gives a quick sense of when umbrellas and waterproof shoes are most useful.
Over the full record (since 1940), the annual mean temperature in Seongnam-si has shifted by +2.4°C between the first decade and the last. The hottest single day in the record reached 37.8°C in 2018; the coldest, -25.9°C in 1951.
Monthly temperature range
August is the warmest month, January the coolest — a yearly swing of 29°C.
Each bar is the average daily low → average daily high for that month. Color shifts cool→warm by month temperature. The dot is the monthly mean. Normal = each month's value averaged across every year of record (1940–2026).
Monthly rainfall
Wettest month: July (~347 mm). Whole year averages ~1356 mm of rain.
Average total millimetres of rainfall in each calendar month, across the full record.
Monthly wind
Average daily peak wind at 10 m, by month.
Monthly solar energy
Average daily incoming solar energy in megajoules per square metre — a measured proxy for how sunny the month is.
Monthly reference table
Numerical reference: average highs/lows, mean rainfall, and absolute records for each month of the year. Normal = each month's value averaged across every year of record (1940–2026).
| Month | Avg high | Avg low | Rain | Record high | Record low |
|---|---|---|---|---|---|
| January | 0.6° | -9.0° | 26 mm | 13.1° (2002) | -25.9° (1951) |
| February | 3.6° | -6.0° | 30 mm | 18.2° (2021) | -23.3° (1984) |
| March | 9.7° | -0.4° | 52 mm | 23.9° (2025) | -16.0° (1971) |
| April | 16.9° | 5.8° | 89 mm | 30.2° (2005) | -4.0° (1941) |
| May | 22.2° | 11.6° | 102 mm | 32.3° (2001) | 2.7° (1945) |
| June | 25.9° | 17.1° | 157 mm | 36.0° (1958) | 9.0° (1974) |
| July | 28.1° | 21.6° | 347 mm | 35.8° (1994) | 11.7° (1954) |
| August | 28.9° | 21.7° | 260 mm | 37.8° (2018) | 12.4° (1972) |
| September | 24.7° | 15.7° | 154 mm | 33.8° (2024) | 4.1° (1957) |
| October | 18.8° | 8.2° | 55 mm | 28.1° (2021) | -3.8° (1958) |
| November | 10.8° | 1.2° | 51 mm | 25.2° (2023) | -13.2° (1987) |
| December | 3.1° | -5.6° | 31 mm | 17.5° (2023) | -22.4° (1973) |
How it has changed
Year-by-year signals from 1940 to today.Climate stripes
Annual mean shifted from 1940–1949 to 2016–2025 by +2.4°C.
Each vertical stripe is one year. Color encodes how much that year's annual mean differed from the long-term average. Normal = each year's annual mean compared to the average of all years (1940–2026). cooler ← → warmer
Hot days vs frost days
Days ≥ 30°C per year: 14.9 early in the record → 39.6 recently. Frost days: 129 → 106.
Thin lines are raw yearly counts; thick lines are the smoothed trend that removes year-to-year noise. The hot-day threshold is auto-picked per city so the line actually moves. Normal = a centered 5-year rolling average to smooth weather noise.
Yearly hot & cold extremes
All-time high in 2018, all-time low in 1951: 37.8°C / -25.9°C.
One point per year — the single hottest and coldest day recorded that year.
Annual rainfall
~1356 mm/year on average. Last decade ran −3% vs that average.
One bar per year of total rainfall. Dashed line is the long-term average. Normal = the average annual rainfall across every year of record (1940–2026).
Day-by-day grid
Each tiny square is one calendar day across the full record — ~30,000 days per city. Use the mode switch above the chart: Anomaly colors each day by how far it ran from the historical normal for that date (red = warmer, blue = cooler), Daily mean temp shows the absolute mean temperature for the day (useful to see seasons and heatwaves), and Precipitation shows daily rainfall (useful to spot wet/dry seasons and droughts). Normal = the long-term average for that calendar date (1940–2026).