The Observatory raised the No1 typhoon signal yesterday as the third tropical storm of the year approached the city. The very hot weather warning remained in force - temperatures soared past 35 degrees Celsius and the air pollution index shot up. The Observatory said it would remain fine and very hot today, but with thundery showers expected tonight. Winds will be mainly westerly. The No1 standby signal was raised at 6.15pm. The Observatory does not rule out raising the No3 signal. Typhoon Nuri is expected to be closest to Hong Kong tomorrow. By early evening yesterday it was 700km southeast of the city and moving west-northwest at about 14km/h. The maximum wind speed near its centre was 144km/h. Earlier yesterday, Nuri swept across the northern Philippine island of Luzon, bringing heavy rain and winds gusting to 170km/h, killing at least five people. Nuri is the third tropical storm to affect Hong Kong this year, following Fengshen in June and Kammuri early this month. A heatwave swept the city as the storm approached yesterday. A maximum temperature of 35.2 degrees was recorded at Pak Tam Chung, Sai Kung. Two women who were taken to hospital with heat stroke; one was discharged and the other was in satisfactory condition. A construction worker was also treated in hospital for heat exhaustion.