The mercury dips to 19 degrees Celsius today as a northeast monsoon brings cooler weather after a week of virtual nonstop rain that was almost as bad as a Covid-mandated shutdown.

But conditions will improve further with a dry continental airstream making itself felt later this week. There will be sunny periods and little chance of rain, though showers and isolated thunderstorms could return on Thursday.

Temperatures will range between 19 and 22 degree today as humidity remains around 80-95 percent. It will be mainly cloudy with a few showers.

The mercury climbs tomorrow to 20-26 degrees while humidity falls to between 65 and 85 percent.

Similar weather with sunny periods will last through Wednesday.

Thursday and Friday should see sunny intervals, but from Saturday isolated thunderstorms will accompany showers.

The predictions of an improvement in conditions came as observatory director Cheng Cho-ming said a new radar system has been under test to see how well it speeds up the prediction of heavy rains in Hong Kong.

But Cheng said it would take years of testing before such a system could be used.

The system currently in use takes about six minute for each scan, but other radar systems can complete the task in about one minute.

"The new radar's limitation is that it has a smaller scan range," Cheng added, explaining: "For a radar to make good scanning it has to scan in all directions. But Hong Kong has many hills, which means many areas are blocked."

Cheng also believes refined radar systems could see Hong Kong issuing rainstorm warnings more frequently in future when the SAR is under the influence of extreme weather.

But, he added, the current warning system is still suitable for use in predicting.

Deluge to fade away amid cooler days