Estimating snow temperature that's far far away...

Tue, Feb  13, 2024 - By Iain Harvey

How can the typical racer who doesn't arrive on the snow until the day of the race know how cold the snow is going to be?

It depends somewhat on where you live/ski. What I mean is many/most places in the winter especially out west have overnight lows that are dramatically lower than the daytime highs. This can be less the case in the northeast and mid-Atlantic. This situation though where the overnight lows are far lower than the daytime highs makes selecting the wax more difficult, so I’ll address that.

In areas where the lows are especially cold compared to the highs, I’d recommend looking at three things:

1. Forecasted overnight low the night before the event
2. Forecasted daytime high the day of the event
3. Start time of the event

Generally speaking at around 7-8am the snow temperature matches the air temperature which oftentimes is the overnight low at this time. From around that point the air warms as the sun comes up and does its thing. Air temperature is a precursor to snow temperature. What this means is as the air warms the snow will also warm but it will lag behind greatly. So maybe at 8am the air and snow are at 5f. If the air is 25f at 11:30am the snow might be at just 12f still. This tricks people into selecting the wrong wax often because they think in terms of air temperature which is only an indicator of what is important which is snow temperature.

We look carefully at snow temperature because it is an indicator of how much free moisture is in the snow. The colder it is the more “frozen” it is and thus there is less free moisture. The warmer it is the more free moisture there is in the snow. So, through looking at the forecasted overnight low and forecasted daytime high (usually later in the day such as 3pm) and anticipating how air will warm between the two and how the snow will also warm but lag behind the air in its warming, you can guestimate what the snow temperature will be when you are going to ski an event.

There are weather stations where you can look at historic air temperatures as well as forecasted air temperatures all over the place and even at different points of ski courses. To improve your learning curve at being able to guesstimate snow temperature at a particular time you can have a snow thermometer and “check your work” on site (take the actual snow temperature and compare it to what you had anticipated) so you learn and can improve at this skill.

So with a 5f overnight low (8am) and a forecasted high the day of the event of 32f with a start time of 11am, the air might be 25f at 11am but the snow will probably still be at around 15f. The temptation might be to wax with red/yellow mix going purely off air temperature for this 11am start, but the correct choice would be a mix of blue and red.

At this point, I'd consider other factors. For example if the snow were transformed (corned up) and fast, I'd probably go with straight red but if the snow were powder and fine grained I'd go with either blue or a blue/red mix. The more windblown the snow is, the colder I would wax (as this dries out the snow a lot).

If it is snowing and accumulating, then the air temperature at which the snow is falling is your reference point. In other words, if it is 20f and snowing (and accumulating), then the snow is about 20f.

I hope this was helpful!