BACKPACKER ALERT, Feburary 2018: Record Low Temperatures Deep Freeze Sierra Nevada Crest

Alex Wierbinski's picture

By Alex Wierbinski - Posted on 24 February 2018




Feb 24
We've been following and warning about these extreme cold temps we've been experiencing since the 17th, but how can we put them into some kind of context?


First, the progression to Full Winter Gear ended on, November 28 of 2017, after which point in time it would be foolish to travel in the High Sierra Backcountry, or to & along the Sierra Crest without FULL WINTER GEAR. That's the date, in my opinion, when temp and weather threats required it, of course with considerations and modifications for subsequent heat waves and cold snaps. We are experiencing just such a cold snap now.

This cold snap is notable, potentially historic. It is far below averages.


It looks like our frigid temperatures are accentuated, if not caused and driven by the Polar Vortex splitting into two around February 12. It currently looks like we have three "Polar Vortices," (EARTH) one of which is freezing us, one that's supposed to freeze Europe all through March, and one that's conducting Arctic air into Siberia and across Central Russia.

Each of the rotating Lows of each of our freak Polar Vorti is conducting massive flows of ultra-cold (to us) Arctic air South.

We are having very cold temperatures.

Compared to What?

South Lake Tahoe and Mammoth Lakes are the closest cities to the Sierra Crest where I can find annual, monthly, and daily average temperatures for, to compare the significance of cold snaps like this one we are currently experiencing on the Sierra Crest and Flanks, with the long-term average temperatures of February.

My research indicates that for the last week or so, since the 17th, both South Lake Tahoe and Mammoth Lakes have both experienced daily highs that are below their average daily low temperature.
These ultra low temps look like they are happening along the whole Sierra Crest between Tahoe and Whitney, as well as both Flanks.

We have been commonly been seeing single-digit and sub-zero overnight temps at altitude.


WINTER of 2018



South Lake Tahoe: Echo Lake & Echo Peak Stations

The Average Daily low for South Lake Tahoe in Feb at Echo Lake is 23 degrees, the high 39.

Average Daily Low for South Lake Tahoe: Echo Lake Station


We've seen daily highs at Echo Peak remain below the average daily low since the 17th.

South Lake Tahoe: Echo Peak California EP5



Mammoth Lakes Station

Ave Daily low for Mammoth in Feb is 16 degrees, high 40.

Average Daily Temperatures, February in Mammoth Lakes

25 degrees has been the highest temp at the Mammoth Lakes station since 6:15 pm on Feb 18! The lowest has been -2.

Mammoth Lakes StationNWS DW5868


More Information and Resources

We've been tracking this Cold Snap on the High Sierra Backpacker's Calendar.


All High Sierra Sensor Systems

We have three systems for checking Temperatures, snow, wind, and other conditions in the High Sierra:

California State System

Federal Snotel System

Federal Mesowest System

All three are linked to from the High Sierra Weather Page, along with a wide range of useful weather tools.



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High Sierra low temperature Backpacker Alert February 2018


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