The air temperature pattern in three urban parks and their surrounding built‐up areas was studied over a one and a half year period in Göteborg, Sweden. The measurements were made at mobile and permanent stations on nights with clear skies and light winds. The maximum temperature difference found between a park and a built‐up area was 5.9°C (summer), and the extension of the cool park climate into the built‐up area was over 1100 m from the park border. Both the extension and the magnitude of the temperature difference depended on the size of the park and the distance from the park border. The green area cooled at a faster rate than the built‐up area, although there were large variations within each area. At the rural station, located at an open site, the cooling was less than at the open part of the green area. Differences in sky obstruction between the sites explained some of the variations in cooling and temperature. However, the relationship between the urban‐park temperature difference and sky view factor was not statistically significant. © 1998 Royal Meteorological Society