Aug da Ross

Graubünden, Switzerland

Tonight: low 8 °C, heavy dew.

Nights by month

Night lows from 2016 to 2025: a typical night, and the cold one that comes 1 night in 10.

The mildest nights are in August, typically 4°C. The coldest are in January, when 1 night in 10 drops to -20°C. Frost is common in January, February, March, April, May, June, July, August, September, October, November and December.

Typical nightCold night (1 in 10)

Jan-14°C -20°CBag comfortable to -19°C · frost 100% · rain or snow 43% of days
Feb-12°C -18°CBag comfortable to -17°C · frost 100% · rain or snow 40% of days
Mar-11°C -16°CBag comfortable to -14°C · frost 100% · rain or snow 39% of days
Apr-7°C -14°CBag comfortable to -13°C · frost 98% · rain or snow 41% of days
May-4°C -8°CBag comfortable to -7°C · frost 91% · rain or snow 57% of days
Jun1°C -3°CBag comfortable to -2°C · frost 38% · rain or snow 57% of days
Jul4°C 0°CBag comfortable to 1°C · frost 11% · rain or snow 56% of days
Aug4°C -1°CBag comfortable to 0°C · frost 17% · rain or snow 51% of days
Sep (this month)0°C -5°CBag comfortable to -4°C · frost 51% · rain or snow 46% of days
Oct-3°C -8°CBag comfortable to -7°C · frost 87% · rain or snow 41% of days
Nov-9°C -16°CBag comfortable to -15°C · frost 98% · rain or snow 42% of days
Dec-12°C -18°CBag comfortable to -17°C · frost 99% · rain or snow 39% of days

| = 0°C

History: ERA5 and ERA5-Land reanalysis via Open-Meteo, corrected to the site's elevation. Bag rating: the comfort rating that keeps you warm in a tent on 9 of 10 nights that month.

Tonight

Good nightFriday, September 25, 22:00 to 07:00

Cold air collects in this hollow

Your setup looks borderline for this night

You may feel chilly from around 06:00.

Your spot sits in a hollow where cold air collects at night.

Best change

Move 20 to 50 meters higher, away from the valley floor or creek.

On clear, calm nights it is often several degrees warmer there.

Change my setup Enter my exact gear ratings

This is based on typical values for the gear types you picked, so treat it as an estimate.

Low outside8°C
Moistureheavy dew, bring everything inside
Windcalm

Your night

22:00 to 06:00ComfortableAir around you 10 to 6°C, heavy dew.
06:00 to 07:00Chilly. Add a layerAir around you 4°C, heavy dew.
07:00 until morningComfortableAir around you 6°C, heavy dew.

Every hour

22:009°Ccomfortable, heavy dew
23:008°Ccomfortable, heavy dew
00:009°Ccomfortable
01:008°Ccomfortable, heavy dew
02:0010°Ccomfortable, heavy dew
03:006°Ccomfortable, heavy dew
04:009°Ccomfortable, heavy dew
05:009°Ccomfortable, heavy dew
06:004°Cchilly, heavy dew
07:006°Ccomfortable, heavy dew

This spot sits about 223 m below the land around it. On clear, calm nights cold air pools here, so expect it colder and wetter than the forecast.

Times are local time at your spot (GMT+2).

What works tonight

The gear this night calls for, for someone who sleeps like you.

You have this
Sleeping bag
Comfort 4°C or colder
The comfort rating on the label, not the limit, which is about 5 °C lower.
You have this
Underneath you
R1.5 or more
The R-value says how well a pad keeps the cold ground out.

Stay safe from carbon monoxideNever run the engine or use a propane or gas heater inside a car, van or tent to stay warm. Carbon monoxide builds up while you sleep and can kill without waking you. Stay warm with layers, insulation and a hot water bottle instead.

Before you sleep

Put on a warm layer and a hat before about 06:00, or go to bed already wearing them.
Eat a proper meal with some fat before bed. Your body keeps burning it through the night.
Pee right before you get in your bag. Getting out at 03:00 in the cold is worse.
Sleep in dry clothes, not the ones you wore all day. Damp fabric pulls heat out of you.
Your spot sits lower than the ground around it. On a clear, calm night cold air drains into spots like this, so expect it colder and wetter than the forecast. If you can, move a little higher up, away from the creek or valley floor.
Bring shoes, clothes and electronics inside. Anything left out will be wet by morning.
Open the tent vents and keep the door zip open a bit at the top. Some condensation inside is normal on a night like this, so bring a small towel to wipe it off.

How we estimated this

At the coldest hour (06:00):

Outside at your spot: 8°C
Warmth your shelter holds: +1 °C
Clear-sky cooling: −1 °C
Low spot: −4 °C
Air around you: 4°C

Your bag's comfort rating: 4°C
Cold ground through what you lie on: +2 °C
Your comfort limit: 6°C

2 °C short, so you will likely be cold.

Assumptions

Bag categories use typical ratings as sold: summer about 50 °F (10 °C), 3-season about 30 °F (-1 °C), winter about 15 °F (-9 °C). The number in a bag's name is usually its lower limit, so its comfort rating is about 9 °F (5 °C) warmer.
What you lie on: foam mat about R2, thin air pad about R1.5, insulated pad about R3.5, winter pad R5 and up, van bed about R4, air mattress about R0.5. Colder ground needs a higher R-value.
Shelters hold a few degrees early in the night and less towards morning. Wind and clear, calm skies take warmth away.
Weather: Open-Meteo forecast for your spot, on a grid of a few kilometers, corrected to its height.
These are rules of thumb, not measurements. People and gear vary.

A forecast, not a promise. Mountains, valleys and water make their own weather, so trust what you see and feel on site. Terms and liability

Checked for a double-wall tent, a 3-season bag and a thin air pad. Check your own gear here.

View on OpenStreetMap