It’s no secret that the temperatures high up in the mountains will be lower than that in the valleys. Have you ever set off on a warm summer hike to find the temps at the peak in the 50’s or worse?
Avoid these surprises by knowing how to calculate the temperature loss as you climb. Here are the steps involved, and a simple equation to reference.
Now, before we proceed, these are simple approximations. They’re not exact, they’re not terribly scientific, and they’re not meant to be used in such a way. Also, if you do the math using Celcius vs Fahrenheit, you will get slightly different values. Again, these are both simplified calculations designed to be done on the fly, they’re not exact. That being said, let’s go on.
- Look up the weather forecast
Obviously, you need a base to go on. Look up the local area forecast, and see what the high, and low temperatures are going to be.
- Determine the elevation of reference for the forecast.
All weather forecasts are referenced to a particular elevation. Using the National Weather Service website you can a detailed forecast, and they’ll list the elevation of reference on the page. If that information isn’t available, it’s usually the same elevation as your official city elevation. Here, we’re at 2,000 feet, and our forecast are all for 2,000 feet.
- Determine your peak elevation
Now you need to know how high up you are going to climb or descend. Reference your topo map, or find these details online. A quick Google with “Mountain (Name) elevation” will normally get you what you need.
- Do the math
You will lose an average 3.5 degrees Fahrenheit for every 1000 feet of elevation you gain. You can also use about 1.2 degrees Celsius per ever 1000 feet, or about 2 degrees Celsius per 100 meters (source for the Celcius calculations). Some people use 9.8 degrees Celsius per 1000 meters).
If you start out at 1000 feet, and climb to 6000 feet, that’s a 5000 foot difference (6000 – 1000 = 5000). So, since you’re gaining 5,000 feet in elevation, you’ll use a 5 in your calculation. 5,000 feet, times 3.5 degrees. Just drop the (thousand). So, ( 5 x 3.5 = 17.5 degrees). So roughly, you’ll expect to lose at least 17.5 degrees. I always round up to the nearest 5 just to factor in changes in weather that can’t be planned for, so here I will assume a 20 degree difference. Simply subtract this number form your expected low, according to the forecast, and you have the lowest expected temperature, short of some crazy weather event.
Ex: The weather man says it’s going to be 60 degrees today for the high in your city. Your city is at 6,000 feet. If you’re climbing from 6,000 feet to 14,000 feet, That’s an 8,000 foot difference. 8 times 3.5 is 28 (8 x 3.5 = 28). You can assume a 30 degree difference after rounding, so it’s only going to be 30 degrees max at the top of the mountain (A high of 60 minus your 30 difference)! Remember, that’s for the high. Always consider your low temperatures too.
Factors that affect your actual temperature
Some factors change the actual value of these calculations. Cloud cover will trap in more heat, where a clear sky will drop the temperature slightly faster. Cold fronts and air streams may also have an effect, as well as local evaporative cooling. These factors are too numerous to account for, so the equation is designed as a general scenario calculation (after rounding).
( 3.5 x Change in elevation)/1000 = temp loss due to elevation change
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