Sierra Vista Southeast, often referred to as Hereford or Nicksville, is a census-designated place (CDP) in Cochise County, Arizona, United States. The population was 14,428 at the 2020 census. It includes the neighborhoods Ramsey Canyon, and Sierra Vista Estates within its boundaries.
thumb|left|Montezuma Pass at [[Coronado National Memorial. The United States / Mexican border fence can be seen in the middle of this photograph. Mexico is on the right / south side of the fence.]]
Geography
thumb|left|Ramsey Canyon
According to the United States Census Bureau, the CDP has a total area of , all land. The CDP elevation is fluctuates greatly, but is measured at above sea level as measured at the Hereford Post Office. Sierra Vista Southeast includes the Huachuca Mountains and part of the San Pedro River. The highest point in the area is Miller Peak in the Huachuca Mountains at above sea level.
Sierra Vista Southeast is southeast of Tucson and north of the United States–Mexico border.
The CDP is built along the San Pedro River, a perennial river. It is the last major undammed desert river in the American Southwest, and it is of major ecological importance as it hosts two-thirds of the avian diversity in the United States, including 100 species of breeding birds and almost 300 species of migrating birds.
Arizona State Route 92 (SR92) runs north to south, connecting the CDP to Sierra Vista and Bisbee.
Climate
In the Köppen climate classification system, Sierra Vista Southeast falls within the typical cold semi-arid climate (BSk) of mid-altitude Arizona. Fall and spring, like most other parts of Arizona, are very dry. Winters are cool to cold with frosts which can occasionally be hard freezes; frost can be expected to stop in mid- to late April. Spring, like fall, spends about half of itself within the frost season. Summer starts off dry, but progressively gets wetter as the monsoon season approaches. The city has a fairly stable climate with very little humidity. However, the North American Monsoon can bring torrential rains during the months of July and August and will produce almost half the yearly rainfall in just those two months alone. Due to the dry climate the rest of the year and the CDP's high elevation, daily winter low temperatures range from on average and up to on rare occasions when moist fronts bring warm air from the Gulf of California. Snow is not a common sight in the CDP, though some years the city can receive several inches of snow and other years it will receive none. However, a snow-capped Miller Peak and Carr Peak in the Huachuca Mountains is a common sight for four to five months every year.
Demographics
2020 census
As of the 2020 census, Sierra Vista Southeast had a population of 14,428. The population density was . The median age was 52.7 years. 18.3% of residents were under the age of 18 and 29.1% of residents were 65 years of age or older. For every 100 females there were 100.6 males, and for every 100 females age 18 and over there were 99.4 males age 18 and over.
56.0% of residents lived in urban areas, while 44.0% lived in rural areas. Of the total population, 6.9% was foreign born.