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Hermosillo, the capital of Sonora, has a hot desert climate (Köppen BWh) that produces some of the highest temperatures of any major city in Mexico. The city sits about 210 metres (690 ft) above sea level in the Sonoran Desert and receives roughly 2,900 hours of sunshine a year. Rainfall totals about 345 mm annually and falls almost entirely between July and September during the North American monsoon. For a fuller picture of when to plan your trip, read our best time to visit Hermosillo guide.
Hermosillo Weather by Month: Winter (December to February)
Winter is the mildest, most comfortable season in Hermosillo. December and January average highs around 24°C (75°F) with overnight lows near 9°C (48°F), so you’ll want a light jacket after dark. February warms slightly to 26°C (79°F). Rain is light, though December is the second-wettest month at 23 mm, and a handful of nights each winter can dip to freezing. Daytime temperatures are pleasant enough for hiking Cerro de la Campana, one of the top things to do in Hermosillo.
Hermosillo Weather by Month: Spring (March to May)
Spring heats up quickly. March averages 29°C (84°F), April reaches 33°C (91°F), and May climbs to 36°C (97°F) with afternoon highs that can touch 42°C (108°F). Rainfall is at its lowest, just 2 mm in both April and May, and skies stay clear. By late May the heat is uncomfortable for midday activity, so plan any walking tour for early morning or evening.
Hermosillo Weather by Month: Summer (June to August)
Summer is extreme. June and July tie as the hottest months with average highs of 39°C (102°F), and Hermosillo has reached 48°C (118°F) in summer on record. Overnight lows only fall to 23 to 27°C (73 to 81°F), so nights bring little relief. The North American monsoon arrives in July, delivering 91 mm of rain in July and 92 mm in August in short, intense storms. Humidity climbs to around 60%, which makes the heat feel heavier. If you do visit in summer, choose a hotel with a pool from our where to stay in Hermosillo guide.
Hermosillo Weather by Month: Autumn (September to November)
Autumn cools gradually. September still averages 37°C (99°F) with 63 mm of rain, but October drops to 34°C (93°F) and November to 29°C (84°F) with lows near 13°C (55°F). By November the monsoon has ended, humidity falls, and the weather is close to ideal for sightseeing and day trips. This is one of the best windows to visit before winter crowds arrive, and it overlaps with the start of baseball season, covered in our events and festivals guide.
Hermosillo Weather by Month: Rainfall and Sunshine
Hermosillo averages about 345 mm of rain per year, and around 71% of it falls in July, August, and September. The city gets roughly 2,900 hours of sunshine annually, among the highest totals in Mexico, with clear skies on most days outside the summer monsoon. The driest months are April and May at about 2 mm each. The table below summarises the monthly averages.
| Month | Avg High | Avg Low | Rain (mm) |
|---|---|---|---|
| January | 24°C (75°F) | 9°C (48°F) | 16 |
| February | 26°C (79°F) | 11°C (52°F) | 15 |
| March | 29°C (84°F) | 13°C (55°F) | 6 |
| April | 33°C (91°F) | 15°C (59°F) | 2 |
| May | 36°C (97°F) | 18°C (64°F) | 2 |
| June | 39°C (102°F) | 23°C (73°F) | 5 |
| July | 39°C (102°F) | 27°C (81°F) | 91 |
| August | 38°C (100°F) | 27°C (81°F) | 92 |
| September | 37°C (99°F) | 25°C (77°F) | 63 |
| October | 34°C (93°F) | 19°C (66°F) | 16 |
| November | 29°C (84°F) | 13°C (55°F) | 13 |
| December | 24°C (75°F) | 9°C (48°F) | 23 |
The city’s hottest stretch runs from mid-June through mid-August, when afternoon temperatures sit near 40°C (104°F) day after day. For practical advice on packing and getting around during the hot months, see our travel tips and FAQ guide.
If you’re deciding where to base yourself, the neighborhoods guide covers each district. You can also return to the main Hermosillo weather guide for a seasonal overview.
