night-time temperature?

[gjanee]

Hi, I'm going up to Rae Lakes in mid-September, which is the latest in the year I've ever gone in the Sierras. At 10,500 feet, any idea what kind of night-time temperatures I might encounter? I'm worried about being cold.

Also, is there a way to get a weather forecast before I go? I know you can get the NWS zone forecast for any area (e.g., https://forecast.weather.gov/MapClick.p ... wMWaC2B2sg), but it's not clear it takes elevation into account.

Thanks!

[bobby49]

My own instinct tells me 20-25 degrees F.

[TahoeJeff]

it's not clear it takes elevation into account.

It does.
Right below the map where you can "Click Map For Forecast", you'll see the lat/long and in parentheses the elevation of your point forecast.

[commonloon]

To add what's been said...

Another good (but not perfect) source is:

https://www.mountain-forecast.com/peaks ... casts/3261

You can also reality check the "Point conditions" w/ another forecast, given the Sierra lapse rate is about 3F per 1000 ft:

Current conditions at
Bishop, Bishop Airport (KBIH)
Lat: 37.37111°NLon: 118.35806°WElev: 4121ft.

..and you're planning on camping at ~10,000 ft (+6,000 ft) -> Low of 73 F @Bishop forecast implies approx low of 55 F @10,000 ft. Of course, East side vs West side will vary a lot, and lots of other factors.

Make sure to bring extra around camp insulation, as well as an appropriate sleep system.... enjoy!

[shampeon]

There's a big difference in temperature based on how moist the area is, and local topography. Choose a site that minimizes being in the cold air drainage. Camping in a meadow or right by a lake at the bottom of a cirque is going to be a lot colder than a spot 10 feet above the valley floor in a foxtail grove on a shelf. Less morning dew on the tent, tarp, bag etc.

[gjanee]

Thanks all!

[Gogd]

@ gjanee

The NOAA map app you refer to in your opening post is what I have used for the last 20 years for near term predictions. In my experience it is very accurate. It does take altitude into account. It will give different reports for Mt Whitney summit and Crabtree Tree Ranger Station, just a few miles apart. It also seems to address the peculiarities of localities, so a general weather system may portend widespread rain for the Sierra, but this app will predict differing levels of activity for the same elevation at Big Pine Creek, versus Bishop Creek and Dusy Basin. I guess they have enough history to have fairly detailed modeling of various micro climates. But I wouldn't get too comfortable with any forecast, after all we are talking about the Sierras!

BTW the forecast indicated by the NOAA weather map in your link is what I would expect of Rae Lakes for this time of year. But come mid September the weather starts getting more variable, the predictions less dependable. The closest field station that could be used to generate a histrionics of seasonal climate data is located at Cedar Grove. Not particularly useful for your purposes. September is a good time to visit the Sierra, as the day time temps can be very pleasant and the nights "good mountain sleeping temperature", but a weather system can bring a cold snap and a dusting of snow. A week long trip can have bluebird days and mild nights, interspersed with storm squalls of rain, hail and light snow. Normally nothing too severe, however; mid September is after the monsoon season, but before the first big storm of fall, which usually happens during the first weeks of November. You can anticipate mid 30s to low 40s night temps in the Sierra @10K' for early - mid September, but the potential for lower temps and weather systems compels coming prepared. You are not likely to get a sustained storm, however, unless it is in the forecast.

Ed

[sukhoi_584th]

The forecast discussion link below the map on the right side of the NOAA page can be helpful too. It will give you insights the pure forecast doesn't. For example a couple weeks ago during a break in the monsoon they noted the clouds would build one day but not reach rain/thunderstorm level, and sure enough that's exactly what happened. Based on what the clouds were doing as the day went on I would have expected thunderstorms if I hadn't read that.

[gjanee]

Super helpful, thank you so much!

[scottmiller]

I usually go in mid-September. I've never had a thermometer with me, but it is usually cold at night. At the coldest, I've had water bottles freeze at night, frost on the sleeping bag, and snow at 8,000 feet. I can usually keep warmish if I put on all my clothes, jackets, rain gear, and so on.
I wouldn't worry about it, though. On a very cold night, get in your sleeping bag early and sleep in the tent. The morning after a decent snowfall is very beautiful.
Out of about 20 mid-September trips, I've had two that were not cold. Many of them were in Emigrant Wilderness, which is generally 8,000-9,000. That was back when you could have a fire, though, so that helped a lot.
On the bright side, I hardly ever get rain in September.