I thought I'd put up this little guide up to help people thinking of traveling over to climb on the Diamond from wasting a journey and to help manage expectations. The info about dew point/air temps can be applied to LPT and other sea-level crags.
The Diamond's an amazing sport crag with world-class routes, but it's location next to the sea means the ambient air temperature, dew point and winds all need to line up to give good crisp conditions. On dry days, when you can climb on inland crags without being aware of any conditions issues, the sea-level crags on the Ormes can be unclimbable if the factors aren't right. This can make for a frustrating experience if you don't know what to expect as the Diamond isn't visible on the handline approach. It also means some people can get unlucky (I've been shut down with the same person twice recently and he doesn't get out any other days..) and end up believing the cliffs are always greasy. They're not at all - and crisp days are the norm in August to early Sept, but there's really no point going on some days when it might seem like a fair bet from the car park.
This is what I've noticed from spending a lot of time at the Diamond:
Dew Point temperature (look it up). It all boils down to this - your enjoyment depends on the size of the gap between the dew point temperature and air temperature. But with some other factors that can help or hinder if the gap is marginal.
Dew Point temperature is always lower than air temperature. It is the temperature at which moisture in the air turns to liquid (condensation). The closer the air temperature is to the dew point, the more moisture will form on the rock. For good conditions on the Diamond the dew point needs to be
at least 6 or 7 degrees below the air temperature (at the local weather station reference point, see below) to stand a chance of the rock not being greasy. If the gap is 6 or 7 you also need a breeze hitting the crag and late afternoon sun. Without wind and sun it's likely conditions will be marginal - i.e. just about dryable with lots of chalk and brushing between each burn.
For good connies, you're looking ideally for a gap of =>8 degrees - then a breeze & sun aren't required. With either is a bonus.
If you ever go there on a day with a =>10 degree gap and it's windy, in the afternoon sun, you'll wonder what all the fuss is about because it'll be like a perfect crisp winter's day on grit.
August has more warm days than September. Dew point gaps are more often larger in Aug than Sept, and by Oct you'll need stormy winds to get good conditions.
Humidity - most of the time this can be used in the same way as Dew Point - 50-75% is a good range, the lower the better. The reason the dew point-air temp difference is a better indicator is because humidity is a relative measure but dew point is absolute. So if the air temperature goes high in summer (some chance) then the relative humidity can remain seemingly lowish while the total amount of moisture in the air has actually risen (warmer air can hold more moisture than colder air).
Wind. The stronger the better. Westerly through north to north-easterly is what you want. The crag faces northwest. In late Sept/Oct look out for the hurricane season in the North Atlantic bringing in tail end high winds to the UK.
Sun. It's usefulness ranges from not required on good crisp days (it can be baking in a nice summer) to essential on marginal days (typical summer this year). The cliff receives sun from 4pm in august but not till 5 in September.
Rain. Doesn't really matter, the crag stays dry and you can climb in the rain (if the dew point hasn't shot up and air temp dropped down). Rain makes the approach very slippery on the old guano. A few of the vertical 7s on the left get a little wet but they quickly dry off.
Seepage. Not an issue for most routes. If there's been prolonged heavy rain the following routes can seep a little though they all quickly dry:
A couple of the vertical 7s on the lefthand side.
Jungle Warfare follows a wet streak
The finish of wall of evening light.
Top of Brutal (8b+) or 8c+ if thinking of extending Diamond Dogs).
Top of The Beast
Pink Star crack seeps if it's been a wet winter/spring (it's bone dry this year..)
Old Chalk. It holds the moisture - brushing it off makes a huge difference on marginal days! On a 30m route it can be a good warm-up just brushing the route if you're well-psyched for the redpoint. Not required on good connies days obviously. Bring lots of chalk and a good brush for marginal days.
Tide Afternoon air temperatures are nearly always higher than mornings. Combined with the crag getting late afternoon /evening sun, it means it's usually best conditions from mid-afternoon to mid-evening before the air cools down too much. Access is possible from 4 hours before low-tide to 4 hours after low-tide. This obviously affects when you can get at the good conditions.. You can get a lock-in on a rising tide, the left-hand side of the crag is non-tidal..
Non-greasy routes / particularly greasy routesBest:
The left-hand wall doesn't suffer from grease anywhere near as much as the central and righthand walls. You can usually climb the vertical 7s left of Non-Tidal Screamer without issues. Also, Empire State (8a, or 8c with the full font 8A start) takes a line of golden rock which doesn't suffer grease as much as The Brute on the grey rock to the right or Never Get Out of the Boat on and left.
(anti)best:
Wall of the Evening light - the black rock at mid-height on this gets greasy first.
The smooth grey rock in the central section (Brute etc.) also.
Predicting conniesTo predict good conditions I use a local amateur weather station located close to sea level in Llandudno. It shows hourly dew point temps along with the other usual stuff. This is the site (WeatherUnderground is really useful):
http://www.wunderground.com/cgi-bin/findweather/getForecast?query=pws:INORTHWA3&MR=1There are a few other stations located close by that all probably show similar readings but I try to use the same one as a reference point. Use the 'change station' tab to choose the '
Alexandra Hotel' station.
The point of using the hourly temps/dew points is that you get a clearer picture of how conditions can be rubbish for parts of the day and great for other parts. It's more precise than what the met office gives you.
Here's what to look for. Today's forecast is looking like good connies for this evening - an 8 degree gap between dew point/air temp, an average NW breeze and sun.
For visual types - if you click on 'graph' and then the 'customise' tab you can add in the dew point and see the hourly dew point/air temp gap in graphical form.
It's obvious from looking at this over a few days that dew-point / air temp gap normally widens through the day to peak around late afternoon and then starts to converge later in the evening.
For trainspotters. You can look at historical data to compare conditions found on the cliff with the day's forecast. Click on the 'almanac' tab.
This weekend - the current forecast shows Saturday looking good, possibly mint. Tides are early though, so you won't get the afternoon sun and the highest air temps which would make it a dead cert for the crag being mint. I'd go, with that forecast.
Sunday's looking marginal. I'd probably not go, unless I was working a section of a route or was prepared to take a chance and suffer a bit.
Obviously you should check the forecast the day before and on the day, it changes closer to the time.
Saturday
