Northern Lights over Lethbridge
You don’t have to go to the Yukon. On the right night the aurora dances over southern Alberta, and here’s how to catch it.
Aurora chances tonight
This live check shows how likely the aurora is from the Lethbridge area right now. Use it with the cloud forecast: a great aurora night is no use under a thick cloud deck.
Checking the aurora forecast…
What is the aurora?
The sun is always blowing a stream of tiny charged particles into space. This is called the solar wind. Now and then the sun throws out a much bigger burst, and it can reach Earth one to a few days later.
Earth’s magnetic field acts like a shield and steers most of those particles away. Some get funnelled down toward the areas around the north and south magnetic poles. When they crash into the air 100 to 400 km above the ground, the air glows. That glow is the aurora: the northern lights here, and the southern lights in the far south.
The colour depends on which gas gets hit, and how high up:
- Green: oxygen, about 100 to 300 km up. This is the colour you’ll see most often.
- Red: oxygen higher up, about 300 to 400 km. It often shows on top of the green during big storms.
- Pink and deep red fringes: nitrogen, near the bottom edge, around 100 km.
- Blue and purple: hard to see by eye, but cameras often catch them.
Alberta aurora photographers helped bring a strange mauve-white ribbon of light to scientists’ attention in 2016. A member of the Alberta Aurora Chasers group suggested the name “Steve,” and it stuck. Scientists now think STEVE is probably not a true aurora at all, but it has been photographed over Alberta and BC.
How often can we see it from here?
More often than most people think. What matters for the aurora isn’t your normal latitude, but your geomagnetic latitude, which is measured from Earth’s magnetic pole instead of the North Pole. That pole sits in the high Arctic north of Canada, so it’s tilted toward us.
Lethbridge is at about 49.7° N on the map, but about 56 to 57° geomagnetic. That puts us further “north” for aurora than many places in Europe at the same map latitude.
On a quiet night the aurora stays over northern Canada. When the sun sends a strong burst our way, the ring of aurora around the pole grows and slides south. Moderate storms bring it into view low in our northern sky. Big storms can put it right overhead.
We sit right where moderate storms reach, under a dry prairie sky with a wide-open northern horizon.
What does the Kp index mean for Lethbridge?
The Kp index is a 0 to 9 scale of how stirred up Earth’s magnetic field is. It’s worked out over three-hour blocks. A higher number means the aurora reaches further south. Kp 5 and above counts as a geomagnetic storm (NOAA’s G1 to G5 scale).
| Kp | Storm level | What you might see from a dark spot near Lethbridge |
|---|---|---|
| 0 to 3 | None | Usually nothing. |
| 4 | None | Sometimes a faint glow very low in the north. Your camera often sees it better than your eyes. |
| 5 | G1 | A fair chance of a glow or arc low on the northern horizon on a dark night. |
| 6 | G2 | Likely visible by eye. It may climb higher, with rays and movement. |
| 7 | G3 | Bright and high, and it may reach overhead. |
| 8 to 9 | G4 to G5 | It can fill the whole sky, even to the south, often with deep reds. These storms are rare. |
Kp is a planet-wide average, and the aurora doesn’t follow it exactly. A Kp 5 night can sometimes beat a Kp 7 night. Sudden bursts can also light up the sky for 20 minutes and then fade. If the numbers look promising, go out and look.
When to look
- Time of night: the best displays usually come within an hour or two of midnight, roughly 10 p.m. to 2 a.m. During strong storms that window opens up earlier in the evening and lasts later into the morning.
- Time of year: any dark, clear night can work. Storms are more common around the spring and fall equinoxes (March and September to October), when the tilt of Earth’s magnetic field toward the sun lets more solar-wind energy in.
- Summer: around June the sky never gets fully dark here, even at midnight, so only bright aurora shows up.
- The moon: a full moon washes out the fainter aurora. It doesn’t make the aurora weaker. It just brightens the sky behind it.
- Cloud: this is the biggest factor of all. Check the cloud forecast before anything else.
In dim light your eyes switch to the cells that are good at faint light but don’t see colour. That’s why a faint aurora can look grey or whitish. A camera gathers light for several seconds and shows the green. If a photo of the northern sky comes out green, the aurora is there.
Where to watch near Lethbridge
You need two things: dark sky and a clear view to the north.
- Go north of the city. Then the city glow is behind you while you face north. Even 15 to 30 minutes out onto the open prairie makes a big difference.
- Find a high spot. A coulee rim or a rise on the prairie gives you a low, flat northern horizon.
- Look away from towns. Small towns and farmyards have lights too. Pick a spot where the northern horizon is dark.
- Use public places. Park Lake Provincial Park is about 17 km northwest of the city (its campground is seasonal). Don’t go onto private land or field approaches without permission.
For more dark spots and the Cypress Hills Dark-Sky Preserve, see our Dark Skies and Stargazing page.
Pull fully off the road onto a safe, wide spot before you stop. Never park on a hill or curve. Don’t stand on the road to take photos. Wear something reflective, and watch for deer. Dress for at least 10 degrees colder than the forecast. Tell someone where you’re going, and in winter carry a kit and check 511 Alberta.
Photo tips
With a phone
- Turn on Night mode (or Night Sight). Turn the flash off.
- Hold very still, or prop the phone on your car roof or a small tripod. On a support, many phones allow longer exposures.
- If your phone has a Pro or Manual mode, try ISO 800 to 3200, a 3 to 10 second shutter, and focus set to infinity.
- Put something in the photo, like a grain elevator, a tree or a person, for scale.
With a camera
- Use a tripod and a wide lens at its widest aperture (f/2.8 or lower if you have it).
- Start at ISO 1600 to 3200 and 5 to 15 seconds. Use shorter exposures when the aurora is bright or moving fast, so the rays stay sharp.
- Focus manually on a bright star, then leave it alone. Use the 2-second timer, and shoot in RAW if you can.
- Cold kills batteries. Keep spares in an inside pocket.
How to read the forecast tools
NOAA 30-minute aurora forecast (OVATION)
This map shows a green oval of predicted aurora around the pole. The oval turns red where stronger aurora is expected. It’s based on solar wind measured by spacecraft well upstream of Earth, so it looks only about 30 to 90 minutes ahead. A bright aurora can be seen from as far as 1,000 km away, so if the oval reaches down over central or northern Alberta, look low in the north.
NOAA 30-minute aurora forecast
The Kp forecast
NOAA’s 3-day forecast gives expected Kp in three-hour blocks. The times are in UTC, so subtract 6 hours in summer (MDT) or 7 hours in winter (MST). The actual Kp is often higher or lower than forecast, because the arrival time and strength of a solar storm are hard to predict.
NOAA 3-day forecast · NOAA Kp index
Canada’s Space Weather Forecast Centre
Natural Resources Canada runs this Canadian centre. It has a quick summary of current conditions and the next few days, plus short-term forecasts for polar, auroral and sub-auroral zones of Canada, rated with levels such as quiet, unsettled and active. The more active the forecast for your zone, the better.
Space Weather Canada forecasts
Dr. Tamitha Skov, “Space Weather Woman”
Dr. Skov is a space weather physicist who posts regular video forecasts in plain language. She shows the sun, incoming solar storms and what to expect, and she speaks to aurora photographers among others.
Alerts
AuroraWatch, run out of the University of Alberta, sends free email alerts. Its measurements are for the Edmonton area, but they’re a useful heads-up for us too.
A day or two ahead, check the Kp forecast. That evening, check the cloud on our forecast. Then watch the 30-minute map and the live check at the top of this page. When it lights up, head out.
Myths and facts
| Myth | Fact |
|---|---|
| The aurora makes a crackling sound. | The lights are 100 km or more up, where the air is too thin to carry sound to us. A few people report crackles on calm nights. One researcher suggests the sound may come from near the ground, not from the aurora itself, but that is still being studied. |
| Cold nights cause the aurora. | No. The aurora comes from the sun and happens in any season. Clear nights just tend to be cold, and clear nights are when you can see it. |
| You can only see it in the far north. | Not true. Moderate storms reach southern Alberta, and strong ones have been seen far into the United States. |
| Winter is the only aurora season. | Winter has the longest nights, but the spring and fall equinoxes tend to bring more storms. |
| If you can’t see colour, it isn’t the aurora. | A faint aurora often looks grey or white to the eye. Your camera shows the true colours. |
Want to understand the weather side better? Try our Weather School, How to Read the Weather and Planning Around the Weather.
Hams love the aurora too
The same storms that light up the sky also change how radio signals travel. Amateur radio operators bounce signals off the aurora itself, and they hear a strange buzzing sound on them. See Aurora and Radio on VE6DOK.net.
Aurora forecasts are rough guides, and no one can promise a show. Always check cloud, road and weather conditions before heading out at night.