Are LED headlights better than halogen headlights in bad weather?

With headlight technology advancing over the years, it does seem archaic to still be comparing halogen headlights and LED headlights. But with most “normal” cars still being offered with halogen headlights, choosing between halogen headlights and LED headlights is still a relevant question for most of us.

We’ve talked about this before, and concluded that if you planned on replacing your current halogen bulbs with aftermarket LED bulbs, the LED bulb would have to mimic the OEM halogen bulb as closely as possible.

However, some say that halogens outperform LEDs in less-than-ideal weather conditions (rain/fog).

How much truth is there to that statement? Let’s find out through a series of questions

Q: LEDs are brighter than halogens, right?

A: Yes. We have no doubt on that. LEDs use less energy to emit a brighter light.

Q: Does LED light travel further than halogen light?

A: This is a matter of light penetration. Whether it is halogen or LED, the light will travel at an infinite distance, should there be nothing to block it (vacuum state). Since we do not live in a vacuum state, light intensity diminishes over distance due to particles in the air.

Water droplets could also refract light, causing them to loose effectiveness.

For better visibility, you would want a good penetrating light.

Q: So, what makes for a good penetrating light?

As it turns out, light penetration is affected by the wavelength. Light with longer wavelength is not refracted as much as light with a shorter wavelength.

Warm light (yellow) has a longer wavelength than cold light (blue).

In simpler terms, warmer light (yellow) penetrates better than cold light (blue). Red light has the longest wavelength, being the colour of choice for taillights and brake lights.

In this Youtube video, you can see just how different coloured lights penetrate fog.

If you look at the “Diff. in %” column, you will see that yellow/warm light has better penetration. The drop in lux reading is lower.

Even the LED yellow light penetrates better than the LED white light.

Since halogen light is generally warm/yellow, we perceive them to perform better in bad weather conditions.

Another factor to consider is the light source pattern.

Q: How does light source pattern affect penetration?

A: By light source pattern we mean either reflector or projector type headlights. Both LEDs and halogen headlights can exist in projector or reflector form.

Projector headlights have a more focused beam, thus improving visibility.

Q: So, this has nothing to do with “halogens or LEDs” at all?

A: Yes. It is about the light colour and the light source pattern. As discussed in our previous article, replacing an OEM halogen bulb with a WRONG aftermarket LED bulb could even reduce your visibility or blind other road users

When the right light housing is matched with the right light source, they will work well.

Q: But LEDs are brighter right?

A: Again, yes. No doubt on that. That's why moving forward, headlight technologies are developed on LED headlights.

Q: Do LEDs cause more glare?

When it comes to this, it’s about matching the right light housing with the right light source. You also need to check the alignment of your headlights to prevent glare to other road users.

Again, this is not a matter of halogens or LEDs.

In fact, modern premium cars are equipped with advanced adaptive headlight technologies that maximise your visibility without blinding oncoming road users.

Summary

So, it seems then that headlight performance in poor weather is affected by the light colour and the light source pattern.

For those who don’t know, LED lights could have warmer tones too. LEDs are undoubtedly brighter than halogen lights and use less energy. However, if used with the wrong housing and misaligned, they could actually make things worse for you.