SINGAPORE: Slather on some sunscreen or seek shade in the afternoon, as the ultraviolet radiation level in Singapore has recorded "extreme" readings this week, reaching the highest of 15 on Monday (Feb 19).

On that day, the one-hour average UV Index of 15 was recorded at 1pm and 2pm, according to the Meteorological Service Singapore (MSS).

This is not the first time Singapore has hit the highest value of 15 on the index. This was also seen at 2pm last Tuesday, as well as at 1pm on both Sept 8 and 17 last year.

However, it is not uncommon for the index to hit extreme levels for several hours during the day.

The UV Index - an international standard measurement of the level of UV radiation exposure - ranges from 0 to 11+ and is grouped into various exposure categories, from low to extreme.

Extra protection against sunburn is needed when the value hits "very high" levels of between 8 and 10, and "extreme" levels of 11 and above, according to the National Environment Agency (NEA) website.

The reading on Monday was first spotted by a netizen, who posted about it on online forum Reddit, firing a discussion among many Singaporeans.

Some of them pointed out instances during the day where they had felt the heat,while others raised concerns about the harmful effects of UV radiation.

Said a Reddit user: "Was wondering why it felt like a sauna in my house. Usually it's really cool here. Was out in direct sunlight for 5 minutes today and it was already too much."

Earlier this month, MSS said that Singaporeans can expect drier and warmer weather, following a mostly cool and wet January.

Some warm days can be expected in the second half of the month, with the daily maximum temperature possibly reaching a high of around 34 deg C, according to MSS' fornightly weather outlook.

On most days, the daily maximum temperature is forecast to be around 32 deg C or 33 deg C, while the daily minimum temperature is expected to range between 23 deg C and 24 deg C.

In response to queries by The Straits Times, an MSS spokesman explained that the weather on Monday had been fair with little cloud cover in the early afternoon.

Over the past two weeks, some of the highest UV Index values recorded included 12 last Friday (Feb 16), 13 last Saturday and Sunday, 15 on Monday and 14 on Tuesday.

The readings were recorded between 11am and 3pm.

The spokesman said that the UV Index varies with factors such as time of day and time of year, latitude (proximity to the Equator), altitude and cloud cover.

Countries near the equator are exposed to higher levels of solar UV radiation.

In Singapore, it is common for the index to reach extreme levels during a four-hour period from 11am to 3pm, when the sun intensity peaks and UV radiation is strongest.

"Under less common conditions when the skies are clear or almost cloud free, more UV radiation can reach the earth's surface," added the spokesman.

According to the NEA website, February is also among the months of the year when the average daily maximum UV Index hovers at "very high" levels. It is an average of 9 in February.

Excessive exposure to solar UV radiation can result in harmful effects to the skin and eyes, the spokesman said.

According to MSS, here are some protective measures to take to minimise the effects if you are out in the sun, especially between 11am and 3pm when the UV index levels are highest:

Use sunscreen (at least SPF 30)

Use an umbrella and seek shade

Wear sunglasses that block UVA/UVB rays

Wear a broad-brimmed hat

More information on factors that affect UV radiation is available here. - The Straits Times/Asia News Network