to it than that. let's head into the bbc weather studios to find out more. so, let's define a heatwave. let's find out what that actually means, and it means different things in different parts of the uk. it's at least three days with the temperature above a certain threshold, and that threshold differs by county. look at this map from the met office which shows the different thresholds. the white areas, for example — all of scotland and northern ireland, much of wales — that threshold is 25 celsius, so at least three days with the temperature at or above that and it's a heatwave. the threshold rises to the darker red around the london area, that's 28 celsius. of course, parts of south east england are more accustomed to higher temperatures than elsewhere. and how do we get hot weather into the uk in summer? well, it's a familiar weather pattern. we draw up high temperatures from africa, from iberia