If you use a formula with only the intercept term, then you will get the mean/average of the dependent variable:
import statsmodels.formula.api as smf
data={'y': [1,5,9], # mean(y) == 5
'X': [[2013], [0.001], [19.99]] # doesn't matter
}
model = smf.ols('y ~ 1', data=data).fit()
model.predict(3.14) # ==> 5