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Hermosillo weather by month: averages, rainfall & climate trends

Hermosillo has well-marked seasons, with 16.8°C between its warmest and coolest monthly means. Rain is a rare event here. Hermosillo weather by month: average temperatures, rainfall, records and how the climate has changed since 1940.

Today vs average

+0.8°Chigh near average

34° / 21°Today
33° / 19°Average
see today in detail →

How it's changed

+1.7°Caverage temperature, 2016–2025 vs 1940–1949average temperature vs 1940–49246days above 30°C a year now (2016–2025) · 208 in the 1940sdays above 30°C · 208 in the 1940s+1.7°C vs the 1940s · see how it's changed →
Weather by montha typical year, averaged over the full recordJanuary, rain 14 mmhigh 24°low 9°February, rain 11 mmhigh 26°low 10°March, rain 7 mmhigh 28°low 12°April, rain 2 mmhigh 32°low 15°May, rain 1 mmhigh 35°low 18°June, rain 3 mmhigh 39°low 23°July, rain 36 mmhigh 39°low 27°August, rain 53 mmhigh 38°low 26°September, rain 41 mmhigh 37°low 25°October, rain 16 mmhigh 34°low 19°November, rain 10 mmhigh 28°low 13°December, rain 18 mmhigh 24°low 10°wettest month August, 53 mm · 211 mm a yearsee month by month →

Right now

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

Right now

34.0°

36°feels like
33%humidity
16°dew point
3 km/hfrom SW
UV index5.9
sunrise06:27sunset17:50day length11h 24m
TodayClear34°21°
MonClear33°22°
TueClear34°22°
WedOvercast34°26°
ThuOvercast31°23°
FriClear29°23°
SatClear29°21°

On this date: October 18

Today (forecast)
34° / 21°
Average for October 18
33° / 19°

High near average · +0.8°C

  • Record high: 40.6° · 2023
  • Record low: 12.8° · 1965
  • One year ago: 31° / 18°

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 Hermosillo is sampled from the ECMWF ERA5 reanalysis at 29.09°N, 110.97°W, with daily records since 1940.

Coordinates
29.09°N, 110.97°W
Time zone
America/Hermosillo
Period
1940–2026
Data source
ERA5 (ECMWF)

Last 30 days

21 of the last 31 days were warmer than the historical average for that date. Average difference: +1.1°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

July brings the year's peak warmth, with afternoons typically reaching 39.0°C and nights around 26.8°C. On about 145 nights a year, the temperature never drops below 20°C. At the other extreme, January brings afternoon highs of about 23.9°C and typical overnight lows of 9.0°C. Freezing temperatures almost never occur.

The annual total in Hermosillo is just 211 mm or so, with August the most likely month to see any of it.

Over the full record (since 1940), the annual mean temperature in Hermosillo has risen by 1.7°C between its first decade and its last. You can follow the shift year by year in the charts below.

Climate graph (climograph)

July is the warmest month, January the coolest: a yearly swing of 17°C. Wettest month: August (~53 mm). Whole year averages ~211 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 23 rainy days a year: most in August (~6), fewest in May (almost none).

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.

Hermosillo 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
January23.9°9.0°14 mm210.3 h34.0° (2003)−1.6° (1949)
February25.9°10.2°11 mm111.0 h36.8° (2009)−1.2° (1985)
March28.4°12.1°7 mm111.8 h39.5° (2007)4.4° (1971)
April31.9°14.9°2 mm012.7 h42.7° (1965)7.3° (2001)
May35.1°18.0°1 mm013.5 h44.1° (1958)9.5° (1951)
June38.9°23.0°3 mm013.8 h46.9° (2016)14.0° (1968)
July39.0°26.8°36 mm413.7 h46.8° (1998)19.8° (1955)
August37.9°26.4°53 mm613.0 h45.5° (2011)19.7° (1990)
September37.0°24.6°41 mm412.2 h44.3° (2024)15.2° (1986)
October33.8°19.2°16 mm211.3 h43.4° (2024)8.6° (1971)
November28.3°13.2°10 mm110.5 h40.7° (2020)4.2° (1994)
December24.1°9.7°18 mm210.1 h33.3° (1954)0.3° (1987)

How it's changed

Year-by-year signals from 1940 to today.

Climate stripes

Annual mean shifted from 1940–1949 to 2016–2025 by +1.7°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: +0.16°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

Mar–May is warming fastest: +0.26°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: 208.0 early in the record → 246.0 recently. Frost days: 0 → 0.

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 2016, all-time low in 1949: 46.9°C / −1.6°C.

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

Annual rainfall

~211 mm/year on average. Last decade: −3% vs that average. Long-term trend: +13 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 Hermosillo

Which is the warmest month in Hermosillo?
On long-term average, the warmest month in Hermosillo is July (mean daily temperature of about 32.4°C) and the coolest is January (about 15.7°C).
How does today's temperature in Hermosillo compare to the historical average?
On October 18, 2026, Hermosillo is forecast to reach a high of 34.2°C and a low of 21.0°C. The long-term average for this date (the full record since 1940) is a high of 33.4°C and a low of 18.7°C, so today's high is 0.8°C warmer than that average.
How much has Hermosillo warmed since 1940?
Comparing the first decade of the record (1940–1949) with the most recent (2016–2025), the annual mean temperature in Hermosillo is about 1.7°C warmer.
How much does it rain in Hermosillo?
Hermosillo receives about 211 mm of precipitation per year on long-term average, with August typically the wettest month.
What is the average temperature in Hermosillo?
Over the full record (since 1940), the annual mean temperature in Hermosillo is about 24.2°C. The warmest month is July and the coolest is January.
What are the average temperatures in Hermosillo by month?
Average daily highs and lows for each month in Hermosillo (°C, full record since 1940): January 24°/9°, February 26°/10°, March 28°/12°, April 32°/15°, May 35°/18°, June 39°/23°, July 39°/27°, August 38°/26°, September 37°/25°, October 34°/19°, November 28°/13°, December 24°/10°.
What is the weather like in Hermosillo in summer?
In summer, June through August, Hermosillo is really hot. Daytime highs sit at 38–39°C and nights at 23–27°C; July is the warmest month. Rain picks up through the season, 3 mm in June to 53 mm in August. No season is wetter.
What is the weather like in Hermosillo in winter?
December to February is winter in Hermosillo, and it is dry and pleasantly warm. Afternoons run 24–26°C and nights 9–10°C; January is the coldest month. Rain eases through the season: 2 rainy days and 18 mm in December, 1 day and 11 mm in February.
What is the weather like in Hermosillo in spring?
Spring in Hermosillo (March to May) is dry and hot. It warms from 28°C by day and 12°C at night in March to 35°C and 18°C in May. Almost no rain.
What is the weather like in Hermosillo in autumn?
Autumn in Hermosillo (September to November) is hot. It cools from 37°C by day and 25°C at night in September to 28°C and 13°C in November. Rain eases through the season: 4 rainy days and 41 mm in September, 1 day and 10 mm in November.
How many days a year does it rain in Hermosillo?
On long-term average, Hermosillo has about 23 days a year with at least 2 mm of rain or snow. The annual total is roughly 211 mm.

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