2020 census

The 2020 United States census counted 45 people, 21 households, and 16 families in Climax.^[9][10] The population density was 375.0 per square mile (144.8/km²). There were 36 housing units at an average density of 300.0 per square mile (115.8/km²).^[10][11] The racial makeup was 95.56% (43) white or European American (95.56% non-Hispanic white), 2.22% (1) black or African-American, 0.0% (0) Native American or Alaska Native, 0.0% (0) Asian, 0.0% (0) Pacific Islander or Native Hawaiian, 0.0% (0) from other races, and 2.22% (1) from two or more races.^[12] Hispanic or Latino of any race was 0.0% (0) of the population.^[13]

Of the 21 households, 23.8% had children under the age of 18; 57.1% were married couples living together; 38.1% had a female householder with no spouse or partner present. 23.8% of households consisted of individuals and 14.3% had someone living alone who was 65 years of age or older.^[10] The average household size was 2.3 and the average family size was 3.1.^[14]

26.7% of the population was under the age of 18, 0.0% from 18 to 24, 20.0% from 25 to 44, 22.2% from 45 to 64, and 31.1% who were 65 years of age or older. The median age was 50.5 years. For every 100 females, there were 87.5 males.^[10] For every 100 females ages 18 and older, there were 120.0 males.^[10]

The 2016-2020 5-year American Community Survey estimates show that the median family income was $68,750 (+/- $28,043).^[15] The median income for those above 16 years old was $20,833 (+/- $8,786).^[16]

2010 census

As of the census^[17] of 2010, there were 72 people, 28 households, and 23 families residing in the city. The population density was 600.0 inhabitants per square mile (231.7/km²). There were 39 housing units at an average density of 325.0 per square mile (125.5/km²). The racial makeup of the city was 98.6% White and 1.4% from two or more races.

There were 28 households, of which 28.6% had children under the age of 18 living with them, 71.4% were married couples living together, 3.6% had a female householder with no husband present, 7.1% had a male householder with no wife present, and 17.9% were non-families. 14.3% of all households were made up of individuals, and 10.7% had someone living alone who was 65 years of age or older. The average household size was 2.57 and the average family size was 2.87.

The median age in the city was 48.5 years. 25% of residents were under the age of 18; 0.1% were between the ages of 18 and 24; 19.5% were from 25 to 44; 23.6% were from 45 to 64; and 31.9% were 65 years of age or older. The gender makeup of the city was 47.2% male and 52.8% female.

2000 census

As of the census^[18] of 2000, there were 64 people, 24 households, and 18 families residing in the city. The population density was 509.3 inhabitants per square mile (196.6/km²). There were 29 housing units at an average density of 230.8 per square mile (89.1/km²). The racial makeup of the city was 85.94% White, 12.50% from other races, and 1.56% from two or more races. Hispanic or Latino of any race were 15.62% of the population.

There were 24 households, out of which 33.3% had children under the age of 18 living with them, 66.7% were married couples living together, 4.2% had a female householder with no husband present, and 25.0% were non-families. 25.0% of all households were made up of individuals, and 8.3% had someone living alone who was 65 years of age or older. The average household size was 2.67 and the average family size was 3.17.

In the city, the population was spread out, with 31.3% under the age of 18, 6.3% from 18 to 24, 21.9% from 25 to 44, 31.3% from 45 to 64, and 9.4% who were 65 years of age or older. The median age was 36 years. For every 100 females, there were 113.3 males. For every 100 females age 18 and over, there were 120.0 males.

The median income for a household in the city was $34,375, and the median income for a family was $40,625. Males had a median income of $42,500 versus $14,375 for females. The per capita income for the city was $14,461. There were no families and 4.1% of the population living below the poverty line, including no under eighteens and 22.2% of those over 64.