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Sanmenxia weather by month: averages, rainfall & climate trends

Sanmenxia swings through a wide annual range, with 27.2°C between the monthly means of its warmest and coldest months. Rainfall is strongly seasonal: the bulk of the year's rain falls between May and October. Sanmenxia weather by month: average temperatures, rainfall, records and how the climate has changed since 1940.

Today vs average

−2.4°Chigh below average

17° / 11°Today
20° / 10°Average
see today in detail →

How it's changed

+1.2°Caverage temperature, 2016–2025 vs 1940–1949average temperature vs 1940–4970frost days a year now (2016–2025) · 86 in the 1940sfrost days a year · 86 in the 1940s81days above 30°C a year now (2016–2025) · 63 in the 1940sdays above 30°C · 63 in the 1940s+1.2°C vs the 1940s · see how it's changed →
Weather by montha typical year, averaged over the full recordJanuary, rain 14 mmhigh 4°low −5°February, rain 21 mmhigh 7°low −2°March, rain 38 mmhigh 14°low 4°April, rain 52 mmhigh 21°low 10°May, rain 72 mmhigh 26°low 16°June, rain 84 mmhigh 31°low 20°July, rain 159 mmhigh 31°low 23°August, rain 145 mmhigh 30°low 22°September, rain 122 mmhigh 25°low 17°October, rain 70 mmhigh 19°low 11°November, rain 37 mmhigh 12°low 3°December, rain 14 mmhigh 6°low −3°wettest month July, 159 mm · 829 mm a yearsee month by month →

Right now

What it's doing today vs the historical average for this date.
Overcast

Right now

11.5°

11°feels like
87%humidity
9°dew point
4 km/hfrom NE
UV index0.0
sunrise06:44sunset17:56day length11h 12m
MonOvercast17°11°
TuePartly cloudy19°12°
WedPartly cloudy15°7°
ThuPartly cloudy12°10°
FriClear16°10°
SatPartly cloudy17°12°
SunOvercast16°14°

On this date: October 18

Today (forecast)
17° / 11°
Average for October 18
20° / 10°

High below average · −2.4°C

  • Record high: 27.0° · 1997
  • Record low: 5.2° · 1987
  • One year ago: 13° / 10°

Every October 18 in history, coldest to hottest

▲ Daily highs▼ Daily lows

Dots show daily highs (top) and lows (bottom) for each October 18 on record (n = 87). Outlined dots are today's forecast.

Area we sample

Each city's history comes from one ERA5 grid cell, about 28 km across, shown by the dashed box. Near mountains or coasts, conditions can vary across the cell.

Location & data

Historical weather for Sanmenxia is sampled from the ECMWF ERA5 reanalysis at 34.78°N, 111.19°E, with daily records since 1940.

Coordinates
34.78°N, 111.19°E
Time zone
Asia/Shanghai
Period
1940–2026
Data source
ERA5 (ECMWF)

Last 30 days

22 of the last 31 days were warmer than the historical average for that date. Average difference: +1.4°C.

Each bar is one day, from morning low to afternoon high. Warm-colored bars are days whose mean ran above average; 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. Average = the day's mean temperature averaged across every year of record (1940–2026) for that calendar date.

This date over the years

One dot per year, showing the mean temperature on this calendar date. Dots are warmer or cooler than the long-term average (dashed line); the shaded band is the typical 10–90% range, and the highlighted dot is today's forecast. Based on ERA5 reanalysis: modelled estimates, not station readings.

Weather by month

Average temperatures and rainfall for each month: a typical year, from the full record.

Climate overview

The warmest month is July, with typical afternoon highs of 31.2°C and nights around 23.2°C. Roughly 80 days a year now top 30°C. The coolest month is January, when afternoons reach about 4.2°C and overnight lows sit around −4.8°C. Around 70 days a year dip below freezing.

Sanmenxia picks up roughly 829 mm a year, with a peak of 159 mm in July and as little as 14 mm in December.

Over the full record (since 1940), the annual mean temperature in Sanmenxia has risen by 1.2°C between its first decade and its last. Recent years have brought less rain as well. The last decade sits roughly 13% under the long-term average.

Climate graph (climograph)

July is the warmest month, January the coolest: a yearly swing of 27°C. Wettest month: July (~159 mm). Whole year averages ~829 mm of rain.

Bars = average monthly rainfall (right axis). Lines = average daily high and low (left axis). Average = each month's value averaged across every year of record (1940–2026).

Rainy days by month

About 75 rainy days a year: most in July (~12), fewest in December (~2).

Bars = average number of days with ≥ 2 mm per month. Hover for the monthly rainfall total.

Monthly wind

Average daily peak wind at 10 m, by month.

Monthly solar energy

Average daily incoming solar energy in megajoules per square metre: the record's own proxy for how sunny the month is.

Sanmenxia month by month: what to expect

Typical conditions for each month, averaged across the full record (since 1940). Daylight is the time from sunrise to sunset. Record high/low are the most extreme values in the ERA5 dataset (modelled since 1940), so they can differ from official weather-station readings.

MonthAvg highAvg lowRainRainy daysDaylightRecord highRecord low
January4.2°−4.8°14 mm29.9 h17.7° (2014)−21.6° (1958)
February7.4°−2.3°21 mm310.7 h23.6° (2021)−19.7° (1952)
March13.9°3.8°38 mm511.7 h31.0° (2013)−19.0° (1951)
April20.9°10.5°52 mm612.9 h36.3° (2006)−1.4° (1962)
May26.0°15.6°72 mm613.8 h38.8° (1980)5.7° (1960)
June30.6°20.4°84 mm714.3 h41.0° (1941)12.8° (1996)
July31.2°23.2°159 mm1214.1 h41.0° (1941)15.9° (1955)
August29.7°22.1°145 mm1113.3 h42.2° (1969)13.9° (1976)
September25.0°16.9°122 mm912.2 h37.9° (2002)7.3° (1970)
October19.5°10.6°70 mm711.1 h32.1° (2013)−0.7° (1986)
November12.4°3.5°37 mm510.1 h27.1° (2023)−12.8° (1993)
December6.0°−2.9°14 mm29.7 h19.9° (2023)−18.2° (1954)

How it's changed

Year-by-year signals from 1940 to today.

Climate stripes

Annual mean shifted from 1940–1949 to 2016–2025 by +1.2°C.

Each vertical stripe is one year. Color encodes how much that year's annual mean differed from the long-term average. Average = each year's annual mean compared to the average of all years (1940–2026). cooler ← → warmer

Annual mean temperature

Long-term trend: +0.23°C per decade.

One point per year, showing the temperature averaged across the whole year. The dashed line is the least-squares long-term trend. Based on ERA5 reanalysis: modelled estimates, not station readings.

Seasonal warming

Dec–Feb is warming fastest: +0.34°C per decade.

Each faint line is one three-month period's average per year; the bold dashed line is its long-term trend. Different parts of the year often warm at different rates. Based on ERA5 reanalysis: modelled estimates, not station readings.

Hot days vs frost days

Days ≥ 30°C per year: 62.5 early in the record → 80.7 recently. Frost days: 86 → 70.

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. Average = a centered 5-year rolling average to smooth weather noise.

Yearly hot & cold extremes

All-time high in 1969, all-time low in 1958: 42.2°C / −21.6°C.

One point per year: the single hottest and coldest day recorded that year.

Annual rainfall

~829 mm/year on average. Last decade: −13% vs that average. Long-term trend: −44 mm per decade.

One bar per year of total rainfall. Dashed line is the long-term average. Average = 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, about 30,000 days per city. Use the mode switch above the chart: Anomaly colors each day by how far it ran from the historical average 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). Average = the long-term average for that calendar date (1940–2026).

Frequently asked questions about Sanmenxia

Which is the warmest month in Sanmenxia?
On long-term average, the warmest month in Sanmenxia is July (mean daily temperature of about 26.9°C) and the coolest is January (about −0.4°C).
How does today's temperature in Sanmenxia compare to the historical average?
On October 18, 2026, Sanmenxia is forecast to reach a high of 17.2°C and a low of 11.4°C. The long-term average for this date (the full record since 1940) is a high of 19.6°C and a low of 10.4°C, so today's high is 2.4°C cooler than that average.
How much has Sanmenxia warmed since 1940?
Comparing the first decade of the record (1940–1949) with the most recent (2016–2025), the annual mean temperature in Sanmenxia is about 1.2°C warmer.
How much does it rain in Sanmenxia?
Sanmenxia receives about 829 mm of precipitation per year on long-term average, with July typically the wettest month.
What is the average temperature in Sanmenxia?
Over the full record (since 1940), the annual mean temperature in Sanmenxia is about 14.2°C. The warmest month is July and the coolest is January.
What are the average temperatures in Sanmenxia by month?
Average daily highs and lows for each month in Sanmenxia (°C, full record since 1940): January 4°/−5°, February 7°/−2°, March 14°/4°, April 21°/10°, May 26°/16°, June 31°/20°, July 31°/23°, August 30°/22°, September 25°/17°, October 19°/11°, November 12°/3°, December 6°/−3°.
What is the weather like in Sanmenxia in summer?
Summer in Sanmenxia (June to August) is wet and hot. Daytime highs sit at 30–31°C and nights at 20–23°C; July is the warmest month. Rain picks up through the season: 7 rainy days and 84 mm in June, 11 days and 145 mm in August. It is the wettest season of the year.
What is the weather like in Sanmenxia in winter?
December to February is winter in Sanmenxia, and it is dry and cold. Afternoons run 4–7°C and nights −5 to −2°C; January is the coldest month. Rain rises from 14 mm on 2 days in December to 21 mm on 3 days in February. No season is drier.
What is the weather like in Sanmenxia in spring?
Spring in Sanmenxia (March to May) is mild. March starts at 14°C by day and 4°C at night; by May it is 26°C and 16°C. Rain picks up through the season: 5 rainy days and 38 mm in March, 6 days and 72 mm in May.
What is the weather like in Sanmenxia in autumn?
September to November is autumn in Sanmenxia, and it is mild. September still brings 25°C afternoons and 17°C nights, November only 12°C and 3°C. Rain falls off from 122 mm on 9 days in September to 37 mm on 5 days in November.
How many days a year does it rain in Sanmenxia?
On long-term average, Sanmenxia has about 75 days a year with at least 2 mm of rain or snow. The annual total is roughly 829 mm.

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