How cold does it actually get?

[mountnman]

I received my overland track map kit from TASMAP in the mail last night, and was reading the information on the back off the 1:100000 map, and under "What to take:", it says it is essential to take a "sleeping bag rated to -5C. (-10C is better).".

Does is really get that cold? I currently use a 0 degree bag here in NSW, even in winter (I've been comfortable down to -5 in it without thermals or a liner). Are they just covering their backsides, or is it really "essential"?

[Son of a Beach]

Yes it does. It occasionally gets down to -5°C in winter at my house in Tasmania, which is about 10m above sea level.

On Tasmania's central plateau, -5°C is likely to happen a few times a year in summer, and frequently in Winter.

My current sleeping bag is rated to -7°C and I've been cold in it once (it was winter, at altitude similar to the OT). My old sleeping bag was rated to around -12°C and I was never cold in that, even sleeping outside on the verandah of an OT hut with snow on the verandah around me.

[Son of a Beach]

PS. Check out the BOM page for Cradle Valley climate showing "all data" at: http://www.bom.gov.au/climate/averages/ ... _All.shtml

It shows that they can get down to -8.5°C at Walheim in August (which is lower in altitude to most of the OT).
Some days it doesn't get above zero at all (in winter).

It can get down to -1, -1.3, -1.9°C in summer at Waldheim, but again keep in mind that it can be even colder on some parts of the OT which are at higher altitude.

[shazcol]

Also note that the MET measures temperature at a standard height of 1.5M above the ground and the actual temperature at ground level can be a lower again.

[mountnman]

Thanks for the link Nik.

Going by that, the coldest it's ever gotten in February is -1.9°C, and that was 40 years ago. If I calculate correctly that the highest campsite is Waterfall Valley at around ~1050m and subtract (roughly) 2 degrees for altitude that is ~-4°C. If I have been comfortable at -5 in my 0 degree bag, I guess I'm asking does a Tasmanian -4 (with a new record) feel colder than a NSW -5?

I don't really want to spend several hundred dollars on something when I already have one that will do the job. Or would I be better just buying a thermal liner just in case?

[Son of a Beach]

It's hard to give definitive advice, because everyone's different in their sleeping patterns, temperatures, and what's comfortable.

But if your sleeping bag keeps you warm at -5°C, then I reckon it should be OK for the Overland Track in February. It would certainly not be warm enough for me, but then I don't have very good internal temperature control, like to sleep with the tent door open (screen door closed), and don't like wearing clothes to bed.

If you're certain it was -5°C then you should be OK for February, I reckon. But be prepared to have to wear extra clothes to bed, if necessary.

[mountnman]

That was a quick reply!!!

I think I will stick with my existing bag, but will get a liner and take thermals (I was taking thermals anyway). If a really good sleeping bag deal comes up I may be tempted into one, but I don't think I'll write one on my "To Buy" list.

And if I do happen to get cold I'll get a new one for the following summer