The work week will start off cloudy and cool Monday but the mercury is set to rise. Here a look at the forecast for London and region: Monday mainly cloudy. 40 percent chance of showers or drizzle in the morning. High 16. Tuesday sunny with a mix of sun and cloud near noon. High 21. Wednesday sunny. High 26. Thursday a mix of sun and cloud with 30 per cent chance of showers. High 29. Friday a mix of sun and cloud with 30 percent chance of showers. High 26.