Ontario

Sister cities

• Brockville
• Winterthur
• East Coast Bays
• Mocorito
• Guamúchil
• Los Mochis

History

Ontario was inhabited by the Tongva people for over 1,000 years. Their country is now known as Tovaangar. The Ontario area was connected to the village of Cucamonga, whose location is not precisely known. The Native and Indigenous histories of Ontario are unknown and underdeveloped, but there are some digital projects. The Spanish Empire's New Spain Portolá expedition found and named the Santa Ana River in 1769. They also explored the Cucamonga area. In 1771, Franciscans from New Spain settled nearby, and established the Mission San Gabriel Arcángel, founding what is today San Gabriel. They enslaved the Tongva people. The area was now part of the New Spain Province of Las Californias. Juan Bautista de Anza passed through the area on his 1774 expedition, which created a land route between the province of Sonora and San Gabriel. An Ontario city park now bear his name. The route became known as the El Camino Real. In 1804, the northern part of Las Californias became the new province of Nueva California. In 1810, the San Gabriel Franciscans took over the Tongva village of Kaawchama (in today's west Redlands), replacing it with the Guachama rancheria. This included a chapel devoted to San Bernardino (beginning the association of the saint with the area). The rancheria was destroyed by the Serrano in 1812, and was rebuilt nearby as the San Bernardino de Sena estancia in 1819. In 1822, word of the Mexican triumph in the Mexican War of Independence reached Nueva California, and the lands previously controlled by the Spanish Empire passed to the custody of the Mexican government. In 1824, the province of Nueva California was renamed Alta California. In 1826, American explorer Jedediah Smith passed through what is now Upland on the first known overland journey from the…

Geography

According to the United States Census Bureau, the city has a total area of . Of that, is land and is water. The total area is 0.13% water. The climate of Ontario is influenced by BSh semi-arid conditions, with hot summers and mild winters. Santa Ana Winds hit the area frequently in autumn and winter. Extremes range from down to . According to the Köppen Climate Classification system, Ontario has a hot-summer Mediterranean climate, abbreviated "Csa" on climate maps.

Race & ethnicity

Most-observed species

• House Finch

  Haemorhous mexicanus (P.L.Statius Müller, 1776) · Aves
  23,562
• Black Phoebe

  Sayornis nigricans (Swainson, 1827) · Aves
  18,979
• Mourning Dove

  Zenaida macroura (Linnaeus, 1758) · Aves
  18,368
• Lesser Goldfinch

  Spinus psaltria (Say, 1822) · Aves
  18,084
• Anna's Hummingbird

  Calypte anna (R.Lesson, 1829) · Aves
  17,806
• California Towhee

  Melozone crissalis (Vigors, 1839) · Aves
  17,153
• Northern Mockingbird

  Mimus polyglottos (Linnaeus, 1758) · Aves
  16,007
• American Crow

  Corvus brachyrhynchos C.L.Brehm, 1822 · Aves
  15,172

Largest nearby schools

• Etiwanda High
  High · Etiwanda · 3,596 students · 25.7:1 ratio
• Chaffey High
  High · Ontario · 3,346 students · 24.4:1 ratio
• Rancho Cucamonga High
  High · Rancho Cucamonga · 3,264 students · 24.7:1 ratio
• Upland High
  High · Upland · 3,070 students · 24:1 ratio
• Los Osos High
  High · Rancho Cucamonga · 2,837 students · 24.9:1 ratio
• Chino Hills High
  High · Chino Hills · 2,800 students · 25.9:1 ratio
• Montclair High
  High · Montclair · 2,769 students · 24.7:1 ratio
• Ruben S. Ayala High
  High · Chino Hills · 2,617 students · 25.4:1 ratio

Most recent

• M 2.77 — 2026-10-15
  3 km NNW of San Jacinto, CA
• M 2.71 — 2026-10-11
  4 km E of San Jacinto, CA
• M 3.16 — 2026-10-09
  2 km SW of Signal Hill, CA
• M 2.7 — 2026-10-08
  2 km WNW of Fontana, CA
• M 2.6 — 2026-10-06
  4 km NNW of Big Bear City, CA
• M 2.51 — 2026-10-05
  31 km SW of Dana Point, CA