The Middlesex-London Health Unit (MLHU) has issued a two-day heat alert as Londoners head into the weekend.
The health unit says the forecast calls for temperatures to climb to a high of 30 C on Saturday, with humidex values reaching 40 C.
The hot and sticky conditions are expected to return on Sunday with a high reaching 31 C.
Even with the forecast calling for a chance of showers or thunderstorms, the MLHU says the conditions over the next two days meet its criteria to issue a heat alert.
The heat alert will remain in effect until Monday morning when the daytime high is set to reach 26 C.