An instantaneous space-weighted ionospheric regional model (ISWIRM) for the regional now-casting of the critical frequency of the F2 layer (foF2) has been developed. The geographical area of applicability of the model is ranged between 35¿N--70¿N and 5¿W--40¿E. Inside this region the hourly values of foF2 are obtained, correcting the monthly medians values of foF2 predicted by the space-weighted ionospheric local model (SWILM) on the basis of hourly observations of foF2 coming from four reference stations (Rome, Chilton, Lycksele, and Loparskaya (or Sodankyla)). The performance of the model, evaluated at four testing stations (Tortosa, Juliusruh, Uppsala, and Kiruna) during some periods characterized by strong solar and geomagnetic activity, can be considered satisfactory, given that the hourly values of the residuals are almost always below 1 MHz. A comparison between ISWIRM's performance using manually validated and autoscaled data of foF2 and SWILM's performance was made for two disturbed periods. One example of instantaneous ionospheric mapping of foF2 relative to the selected disturbed periods is also shown.