The oh– concentration in a 1.0  10–3 m ba(oh)2 solution is

The Ionization of Ba(OH)₂ is as follow,
           
                                Ba (OH)₂    →     Ba²⁺   +   (OH⁻)₂
Or,
                                Ba (OH)₂    →     Ba²⁺   +   OH⁻    +    OH⁻
As,
Concentration of Ba(OH)₂ is 1.0 × 10⁻³, and each Barium Hydroxde contains two OH⁻ then concenteration of OH⁻ is calculated as,

                               [OH⁻]   =   2 × 1.0 × 10⁻³

                               [OH⁻]   =   0.002 M
Or,
                               [OH⁻]   =   1.0 × 10⁻³

If the water vapor content stays the same and the temperature drops, then the relative humidity increases. its vise versa.if the water vapor content stats the same and the temperature rises, the relative humidity decreases. so, yes, i'd say that temperature and humidity have a strong relationship.