UKH

I am hoping to bivvy in Snowdonia in April, although planning on waiting for a dry weekend, so more likely in May the way the weather has been. First time bivvying.

Two nights with both around the 1000m mark.

I'd like to avoid getting a new sleeping bag, which is a lightweight down bag with a comfort level down to 5 degrees (untested at that temperature).

I was looking at past weather on Snowdon using this site: https://www.timeanddate.com/weather/@2637568/historic?month=4&year=2023

According to this, the temperature in April 2023 hardly ever dipped below freezing. Is this likely correct? In May on the other hand it very rarely dips below 5 degrees at night.

It's been a while since I've walked in Snowdonia, but I'm sure I recall it being freezing in the mornings, most mornings this time of year.

If my memory is to be believed, I may struggle and should bring a big down jacket to stay comfortable at night (or get a warmer bag).

If the above link is to believed, my very lightweight down jacket which I will bring anyway is all I probably need with my current bag.

Anybody recall typical night temperature in April/May at 1000m?

If it's dry you should be fine with bag + clothing. I'd worry more about unpredicted rain - are you going to use a bivvy bag?

I think the answer is - it depends! Certainly April, and even May, can see anything from snow through to minor heatwave. You're probably right that a 5 degree bag is not going to cope with all the conditions you might come across. But you already seem to be planning on waiting for a suitable weekend, so as well as looking for a dry weekend forecast I'd be looking at the MWIS and Met Office forecast temperatures for the summit before making my decision on whether to go or not. And if you haven't used it at those temperatures before I'd also try your bag somewhere close to home first at a temperature close to what you think is its limit, to get a better feel for how it will perform before you're relying on it in the middle of nowhere.

You'll get covered in dew, so a bivy bag might be a good idea. They also increase the temp rating of your sleeping bag. You can get fleece liners for sleeping bags, which may pack smaller than your down jacket. But still bring your jacket. A midge net would  be a good idea as well.

27th May 2021 - Top of Moel Saibod...
Look at the ice on the lightweight bivi bag...

I did not take my heavier Gotetex bivi
But did have my 4-season bag..

I find it's the legs and feet that get it, if I take my 3-season bag and the temps drop..
Down boots (Rab or Montane) help with the feet, and something like Montane Prism pants can help out whilst you are at your bivi site, wandering around at dawn taking photos, and also give you an extra layer at night to keep the lower half warmer....
 

I forgot to mention...
A good mat, or even mats really make a difference...
If money is tight... A cheap, but wide foam mat first... and then an inflatable mat on top... 
You feel the cold through the floor first (in my experience)!!

Yes, you'll at some point be too cold.

Probably about half an hour after you thought to yourself, "I can't believe how comfortably warm I am".

You'll also put off going for a wee for about 2 hours, thinking it'll wear off. It won't; just get straight up and go.

And you would, if your hearing was good enough, hear every hour being announced by a church bell in Llanberis, as you continue to lie on the ground pretending you're asleep.

I love bivvying, you get to lie awake and look at the stars and have plenty of time to reflect on how awesome a place you're "sleeping" in.

Maybe it's just me.

Yes, I have a cheap and simple non breathable bag + decent blow up and geo matts. And a pillow, need a bit of luxury.

I hope I get some sleep. The day between the two nights is planned to be a pretty big day. 

This is exactly what I have.

I would still suggest you try out this setup close to home before you use it in anger on top of a mountain. I'm not saying you can't make it work, but I have spent a night in a "cheap and simple non-breathable bivvy bag", and I was astonished at how wet (from condensation) and hence cold I was by the time I woke up. I honestly think, unless its actually raining, you'd be better off sleeping on a non-breathable bivvy bag, not in it!

You'll want to make sure that you eat enough - being short on calories will make you colder and a typical 600 calorie freeze dried pack won't be anywhere near enough dinner for a 'big day'.

Also you will most likely be pretty cold in a bag with a EN limit rating of 5°C up the hills in April or May.  The site you're using looks to be giving historic weather information for Capel Curig approx 200m above sea level, at 1000m it will be 5-10 degrees colder.  And windier.

What sleeping bag is it?

Sounds like an awful honeymoon plan

It's a "Extreme Lightweight Down Winter Sleeping Bag Red" from mountain warehouse. Not on their site anymore so I can't link it. It's probably not extreme either.

If you use the link below it definitely says "Snowdon - Yr Wyddfa" with the exact same data and is labelled as such when searching for the data, but for some reason (worryingly) gives a weather forecast for Capel Curig. Does make me doubt it.

https://www.timeanddate.com/weather/@2637569/historic?month=4&year=2023

Just as a check, here is the Capel Curig data: https://www.timeanddate.com/weather/@2653850/historic?month=4&year=2023

Exactly the same. Doh!

I'm glad you spotted that. This site doesn't make it easy to know what data you are looking at.

First night food wise will be fine. Not going up until afternoon so plenty of time to get calories in. It's the second night that will be a challenge as we need to carry it all.

It's pretty heavy but I've got a Rab jacket (Neutrino Pro if I remember rightly) which if nothing else will keep my chest warm.

Is that s degrees for the comfort or comfort limit temperature. If comfort limit, I think you need a thicker bag. If comfort, you might be ok?

This is what I was going to say. 

The earth is trying to make your body the same temperature as the earth. Your body is trying to make the earth the same temperature as your body. The earth will win! So ground insulation is super important. 

I also think the biggest puffy jacket you can find is a big help too. Warm core = warm extremities. 

Have a blast! 

Agreed. The one time I have ever slept in a orange survival it was low level and mid summer. I woke up absolutely soaked from condensation and shivering. 

So, this one perhaps: https://www.amazon.co.uk/Mountain-Warehouse-Extreme-Lightweight-Sleeping/dp...

I think it sounds a great trip you have planned, but I'm afraid I think with this sleeping bag and a non-breathable bivvy bag the simple answer to your question is "Yes", and possibly "Very".

Yep - down bags collapse with surprising rapidity even in a goretex bivvy bag from condensation not getting out. You'll be comfy for a night, but even a second night can be noticeably more miserable and that with a breathable one! 

Montyjohn, stringing up a simple tarp on your walking poles above you it way better than trying to sleep in a plastic survival sack. 

I think I missed the 'Non-breathable Bivi bag'....

Don't do it...

In the picture I posted earlier, I was using this one..
https://www.summittosea.co.uk/dpt/tents-shelter-sleeping/rab-survival-zone-...
As you can see from the ice build up.. It does breath (Pertex)... but it's fairly snug around the sleeping bag. 
This does cause some dampness. 

I prefer the larger Gore-tex bag... 
https://www.uttings.co.uk/p100468-terra-nova-apollo-bivi-tent-green-52a-g/

This has more volume which appears to allow some air to stay in between the bag and the shell, and therefore breath better. 

Keep a look out for secondhand GT bags, I got a spare that my daughter now uses (from here), and after a reproof and reseal... Its great. 

I use, and fully love, my ex-army bivvy bag. It's old and goretex and a bit too bulky anf heavy but it's bombproof and it breathes. 

As others have said, don't use the unbreathable bivi bag: you'll be soaking wet and your bag won't dry out.

If it's not raining, just find a spot out of the wind, and as recommended, max out the sleeping mats.

If raining, and you're somewhere along the track up to Snowdon from Pen y Pas, I remember some old drift mine shafts that made excellent bivi sites. If you're heading up into the Devil's Kitchen in the Ogwen valley, there's a choice bivi in a hole under a huge boulder - big enough for three. The only other bivis I did were either way over east, or in the doorway of a loo in the carpark at Nant Peris.

But the best is a dry night and open skies.

In April, nights will still be long, so bring extra batteries for your lights.

You might be setting yourself up for some 'type 2' fun, but it'll be a weekend to remember, which ever way it plays out.

Most likely, you will be cold and damp. Echoing others plus some new thoughts:

- Borrow or buy a breathable bivvy bag. Alpkit have great value ones.

- If on Snowdon there are some wind shelter options around the summit building, including a small porch area.

- Take kit for a hot brew before bed, for breakfast, and possibly for during the night. Keep this within reach so you don't have to get out of your bag.

- Light gloves, dry clean socks and a hat will make you more cosy.

- Fatty foods like cheese and salami style sausage seem to help me sleep warmer. Eat well. Do a few sit ups before zipping up.

- You can add hot water to your water bottle ( if suitable ) and cuddle this.

-With the right kit this can be a wonderful experience.

-For some people an eye mask and ear plugs help.

My tip re bivvy bags is consider sleeping on/next to it until it starts to actually rain, and only then get into it. I have an Alpkit one, and anything less than a light drizzle and I land up drier/warmer not inside due to condensation.

"Do a few sit ups before zipping up."

This is what people get wrong in all forms of camping. Do 30 star jumps, sit ups or whatever. Don't get sweaty but get in your bed with a bit of warmth already emanating. Your sleeping bag only stops your heat escaping by insulation; it can't magically warm you up if you got to bed cold, but a warm body in an insulated bag makes for a cosy time.

Ok, so I think I know what I'm going to do based on feedback.

• As planned, wait for a dry weekend that doesn't have some abnormal northerly wind.
• I'm going to buy a breathable bivvy bag. May just go with the https://www.summittosea.co.uk/dpt/tents-shelter-sleeping/rab-survival-zone-... as suggested above or maybe the https://alpkit.com/products/hunka?variant=31071902826601
• I'm going to take my big duvet jacket instead of my lightweight down jacket. Positron Pro from Rab. Think it weighs about 600g.
• And take my 5 degree comfort level sleeping bag (I know, but want to keep costs down)
• With a blow up and z-foldy geo mat thing.

I know the down bag may be the weak link in the above, but the jacket is very warm and I hope will make up for it.

I figured if the list above is wrong, it's just going to be an uncomfortable night, probably cold legs, I think I can live with that. And if it's worse than I expect then I'll know for next time.

Thanks for the feedback. Really helpful.

Hopefully the downvotes from the original post are dealt with above, if not, please let me know as the downvote doesn't really guide me much.

I have a only used once* Alpkit Hunka (black) if you want to keep the costs down. Drop me a message.

*Lightweight tent for me nowadays....

I suspect that you're underestimating how miserable it is to be too cold for 6-8 hours, unable to sleep.  Uncomfortable is a mild word.

Add in a sleeping bag liner? Will make more difference than you suspect! I've done my fair share of bivis around Eryri, with a similar set up to the above (admittedly with a more fancy down sleeping mat) and have never really had an issue. 

This is the beauty of a bivi though - if its shit, you can just get up and start your day early without too much faff

Even at freezing, you will be absolutely fine with a mat, a bag and a jacket. Now rain.....ha, that's another matter.

Have you ever bivi'd for one night? The challenge with bivis or camping over multiple days is damp kit. If your first night is bit naff, the second with be truly miserable if everything is damp already. For Multi day bivi-ing to be comfortable you really need good weather or some form of additional shelter, old buildings, snow hole etc. 

Have bivi in *August* with a 10C comfort and 5 C "extreme" rating at a touch over 1,000m in Wales last year and one year to the day (by coincidence) the same spot the year before. In the distant past I used to very occasionally bivi bag round the back of the old Snowdon summit station including in snowy conditions. The new station is not a good spot for bivi.

My personal observations are:

The comfort temperature ratings sleeping bag manufacturers give are wildly different per person and per manufacturers, with some numbers pretty dishonest, but some (like snugpak) are pretty fair. If you've not used this kit in those temps before, be cautious.

Temperature at 1000m is usually a LOT colder than the forecast for Llanberis/Capel Curing. Maybe obvious but this bears repeating!

Dampness... dampness... nothing is as warm and nice as in the dry. Damp tolerant stuff advised as it looses warmth, but less dramatic than say... down

Have a decent foam mat like thermarest ridge rest *and* an ultralight air mat

If you have a big army style bivi bag get the air mat inside the bivi bag and the ridge rest underneath the bivi bag

I'd say expect the worst, 5C and damp and windy for your bivi. If you do better than that good luck. If really unlucky colder like zero, unlikely! but possible...

Edit: sea to summit Spark sp1 bag - not warm enough at all, Rab alpine bivi bag, no proper cooker, wearing all clothes I had! Miserable! But in my case I needed to be as small pack size and light as humanly possible (don't ask, there was a reason)

You've got excellent advice from numerous posters who have bivvied in the hills.  Its how  they  got experience.   

Have you thought about going out  yourself somewhere locally convenient  to bivvi just for one or two nights, then you'll have a reasonable idea what you need to do or buy?

I would say that Snugpaks are some of the worst for exaggerating the warmth of their bags. They claim to be far warmer than pretty much every other bag of similar specs on the market. 

Good post.

4° forecast overnight in Purley/ London this weekend. Good time for a test bivi, montyjohn !

Don't forget one of those lightweight absorbent towels. Good for wiping away those bitter tears of misery.

I was planning to, but then it rained every day for as long as my memory can think back.

I would be very unhappy sleeping in my neck of the woods, in the mud, in the rain, over-run with badgers and foxes (you won't believe how many there are here).

The next really decent weekend we get, I'm not squandering it at home, I'm off.

Just fished out my bag to double check.

5 deg - comfort

0 deg - limit

-10 - extreme.

As recommended on here, I've got a fleece liner I can bring. Plus a big down jacket.

Assuming you have a headtorch, the worst case scenario is probably that you can't get to sleep because you're too cold. You can always get up and walk downhill.

If you have a garden you could always try out your setup there first? Won't prove it's warm enough, but might let you know it's not.

Through experience I've learnt bivis are best within 1km of a pub, evening meal, warmth, a few pints, stumble back to your secret hide away (behind last wall up onto fells), last pee, then straight to sleep! 

Note. Don't forget to take headtorch to pub. 

Have you got a garden? If so, that's your testing solution! Some of my early UKC sleeping bag tests were partly conducted on my back porch or in a snow scrape out on the "lawn" when I still lived in Helsinki. It was actually great as the forecast was pretty accurate for the next 12 hours so by tea time you had a good idea what the overnight temp would be, and if that was the comfort limit of the bag, it was get out there and check it was accurate! The last two pics in this one https://www.ukclimbing.com/gear/camping/sleeping_bags/mountain_equipment_sn... are very adventurous back garden tests! 😀

I agree, some people haven't learned this trick yet - which is why I mentioned it... The hot water bottle is still my favourite though.

You've reminded me of a fun bivvy. Perched on a rock by the old Abri Simond hut surrounded by snow, ice and cloud I was brewing up a hot chocolate for my wife and son who were bivvying with me. As we slurped the drink my wife commented that this was our wedding anniversary and that it most definitely was not the romantic evening she had hoped for...

The best way to sleep when bivvying is to be too tired to stay awake, with enough food inside you and an empty bladder. Don't expect a good nights sleep though, or even much sleep at all if it rains.

Purists may scoff but an eye mask helps - because it always gets light before you want it to.

Take a lightweight stove and heat up some water, you can put it in a nalgene (with some sort of cover) and you've got a hot water bottle. With an insulated cover it will last most of the night.