R^2 is the percent of variance in the DV accounted for by the whole model. That is, your intercept and your IVS combined account for that much of the variance, using the linear regression model.

In your case, you got an R^2 of 0.85, indicating that intercept, plus cdd plus pmax combined account for 85% of the variance in the DV. The other 15% is error. That is, variance that is not accounted for by the model

You cannot tell, from the information given, how much of this 85% is contributed by each. In order to do this, you would have to run more models:

DV ~ . (intercept alone) DV ~ cdd DV ~ pmax

Each of these would have an R^2, and you could then tell how much each adds.

R^2 is the percent of variance in the DV accounted for by the whole model. That is, your intercept and your IVS combined account for that much of the variance, using the linear regression model.

In your case, you got an R^2 of 0.85, indicating that intercept, plus cdd plus pmax combined account for 85% of the variance in the DV. The other 15% is error. That is, variance that is not accounted for by the model

You cannot tell, from the information given, how much of this 85% is contributed by each. In order to do this, you would have to run more models:

DV ~ . (intercept alone) 
DV ~ cdd 
DV ~ pmax

Each of these would have an R^2, and you could then tell how much each adds.