A lot of research has been conducted in the past decades on urban heat island (UHI) all over the world. Nevertheless, the UHI effect has not been included in weather data used by building services engineers to design buildings and size their heating and cooling plants. This research was carried out to investigate the UHI effect in Greater Manchester by setting up fixed point monitoring stations over the city. Woodford Met Office ground observation station was selected to be the rural reference point. A multiple regression model was developed to incorporate the heat island effect into the Manchester weather data for engineering usage.It was found that the urban heat island intensity (the difference between the rural and urban area temperatures) can be as high as 8oC in summer and 10oC in winter in Manchester. Clear and calm nocturnal temperature data was used (when maximum heat island occurs ) to find the relationship between the UHI intensity and sky view factor (SVF), distance away from the city centre, evapotranspiration fraction (EF), wind speed, cloud cover and rural reference temperature. Results indicate that all factors have a negative linear relationship with UHI intensity. All measured data were fed into a statistical software package to create general linear regression models. Validation showed that these models were capable of predicting average UHI effect to a good accuracy. The maximum heat island effect peaks are not so accurate. However, an analytical model was developed based on energy balance equations to predict the maximum heat island effect. Validation shows a good prediction for summer but not so good for winter. This is probably due to the lower average UHI intensity in winter than in summer.