Explainer · Sun and pigmentation

Singapore's UV Index and Your Skin what the numbers mean for sun spots and melasma

A sourced guide to how the UV index is measured in Singapore, why it runs high close to the equator, what UV does to pigmentation, and the protection steps official agencies recommend.

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Written & medically reviewed by Dr Sin Yong · 9 October 2026

Quick answer

According to Singapore's National Environment Agency (NEA), it is common for the UV index here to reach Very High (8–10) and Extreme (11+) between 11am and 3pm on days with little cloud cover.
The World Health Organization notes that at a UV index of 3 or higher there is an increased risk of skin damage and protective measures are recommended.
UV exposure drives sun spots and is a recognised trigger for melasma, which researchers have described as a photoaging disorder; visible light has also been implicated in melasma.
NEA's sun-protection advisory, sourced from the Ministry of Health: use sunscreen of at least SPF 30, use an umbrella and seek shade, wear UVA/UVB-blocking sunglasses and a broad-brimmed hat.

The scale

What the UV index measures

The UV index (UVI) is an international standard developed jointly by the World Health Organization, the United Nations Environment Programme and the World Meteorological Organization. It describes the level of solar ultraviolet radiation at the Earth's surface, depends on both UVA and UVB, and runs from 0 to 11+. A higher number means a greater potential for harm to the skin and eyes.

In Singapore, NEA measures the UVI with a sensor in an open field at the Changi Meteorological Station and reports it every 15 minutes between 7am and 7pm; each reading is the average over the previous 15 minutes. Rain and cloud reduce the value, so NEA notes that the UVI may vary in other parts of the island.

UV index	NEA category	WHO guidance
0–2	Low	You can safely enjoy being outside
3–5	Moderate	Seek shade during midday hours
6–7	High	Seek shade during midday hours
8–10	Very High	Avoid being outside during midday hours
11+	Extreme	Avoid being outside during midday hours

Why it runs high here

Close to the equator, strongest from 11am to 3pm

NEA explains that UV radiation and UVI values are highest near the equator and decrease with increasing latitude. At lower latitudes, sunlight passes through a shorter distance of atmosphere and is concentrated on a smaller area when it reaches the ground. Singapore lies just north of the equator, so the midday sun is high overhead.

NEA states that it is common for the UVI in Singapore to reach Very High and Extreme levels in the four-hour period between 11am and 3pm on a day with little cloud cover, and that values are typically close to zero at night. The index runs higher in months with less cloud and when the sun is directly over the equator. Thick cloud and rain can absorb or scatter much of the UV and keep the midday reading down, so the sky on a given day matters as much as the season.

Two further points from NEA are useful for context. The ozone layer blocks almost all UVC and much of the UVB, so most of the UV reaching the ground is UVA. And UV increases with altitude, because thinner air filters less of it.

Why it matters for pigment

Sun spots, post-inflammatory marks and melasma

Sun spots (solar lentigines) are small, defined brown marks scattered where the sun hits most, such as the cheekbones, temples and backs of the hands. Post-inflammatory marks sit exactly where a breakout or injury was, and can darken further with sun exposure. Melasma looks different: symmetrical, soft-edged patches across the cheeks, forehead or upper lip that tend to darken after sun or heat.

Melasma has long been linked to hormones and genetic predisposition. In a 2018 review, Passeron and Picardo summarised newer evidence on how it develops and suggested that melasma might be a photoaging skin disorder affecting genetically predisposed people, a view with direct consequences for prevention. Light beyond UV matters too: in a double-blind randomised trial of 68 melasma patients exposed to intense sun, a sunscreen containing iron oxide to absorb visible light, used alongside a depigmenting treatment, gave greater improvement over eight weeks than a UV-only sunscreen; both had an SPF of 50 or more.

Daily protection also affects how skin ages. In a randomised trial of 903 adults in Nambour, Australia, people assigned to daily broad-spectrum sunscreen showed no detectable increase in skin ageing after four and a half years, and less ageing than those who used sunscreen at their own discretion.

Daily protection

The basics, as recommended in Singapore

NEA's advisory, sourced from the Ministry of Health, notes that some UV exposure matters for health, including vitamin D production, but that excessive exposure harms the skin and eyes. If you must be out in the sun, especially between 11am and 3pm, it recommends these measures:

Use sunscreen of at least SPF 30.
Use an umbrella and seek shade.
Wear sunglasses that block UVA and UVB rays.
Wear a broad-brimmed hat.
Check the current reading: NEA publishes the UVI every 15 minutes between 7am and 7pm.
If you are prone to melasma, ask about a tinted sunscreen with iron oxides, which also absorbs visible light, in line with the trial evidence above.

When to see a doctor

Signs that need a medical opinion

Only a doctor can diagnose pigmentation. At IN Eternity Clinic, 9 Scotts Road, Pacific Plaza, beside Orchard MRT, Dr Sin Yong assesses the type and depth of pigment before recommending a medical plan, which is priced at consultation by the clinic. SkinRev Lab, a non-invasive aesthetic centre at CityLink Mall, can help with surface care and daily protection, but does not diagnose or treat melasma.

Symmetrical, blotchy patches on the cheeks, forehead, upper lip or bridge of the nose that darken after sun or heat, which may be melasma and need a doctor's diagnosis and plan.
A new spot that looks different from your others, or any spot that changes in size, shape or colour, bleeds, itches or does not heal.
Pigmentation that has not shifted despite gentle skincare and daily sun protection.
Pigment changes during pregnancy or while taking hormonal medication, which are worth discussing with your doctor.

Key figures

For quick reference

The UV index runs from 0 to 11+, grouped as Low (0–2), Moderate (3–5), High (6–7), Very High (8–10) and Extreme (11+). Source: NEA.
Singapore's UVI is measured at Changi Meteorological Station and reported every 15 minutes from 7am to 7pm. Source: NEA.
Very High and Extreme readings are common between 11am and 3pm on days with little cloud. Source: NEA.
Protective measures are recommended at a UV index of 3 or higher. Source: WHO.
Recommended measures: sunscreen of at least SPF 30, shade or an umbrella, UVA/UVB-blocking sunglasses, a broad-brimmed hat. Source: NEA, citing the Ministry of Health.

Sources

References & sources

Common questions

Your questions,
answered

What is a typical UV index in Singapore?

It varies through the day. NEA says it is common for the UVI to reach Very High (8–10) and Extreme (11+) between 11am and 3pm on days with little cloud cover, and that readings are close to zero at night.

When is UV strongest in Singapore?

Usually in the four hours between 11am and 3pm, according to NEA. The index also runs higher in months with less cloud and when the sun is directly over the equator.

Is the UV index lower on cloudy days?

Thick cloud and rain can lower it, according to NEA. Because readings vary across the island and conditions change during the day, it is more reliable to check the current reading than to judge by the sky.

Does UV cause melasma?

Melasma is linked to hormones, genetic predisposition and light. UV and heat tend to darken it, researchers have described it as a photoaging disorder, and a randomised trial found that adding visible-light protection improved results. A doctor should confirm the diagnosis.

What SPF should I use in Singapore?

NEA's advisory, sourced from the Ministry of Health, recommends sunscreen of at least SPF 30, together with shade or an umbrella, UVA/UVB-blocking sunglasses and a broad-brimmed hat.

When should I see a doctor about a dark spot?

See a doctor if a spot is new and looks different from the rest, changes in size, shape or colour, bleeds, itches or does not heal, or if you have symmetrical patches that darken after sun. Dr Sin Yong sees patients at IN Eternity Clinic, Pacific Plaza; WhatsApp +65 8815 3008.