Transamerica trail temperatures

[Stevekeating]

Leaving Virginia in early may and finishing in Seattle  beginning of july  what kind of low temperatures  should I be expecting.

Thanks

[jamawani]

Prism has monthly maps of temp hi/lo/mean & precip.

http://prism.oregonstate.edu/normals/

[walks.in2.trees]

Wunderground.com from a WEB BROWSER (not in the App) on any device
Click on the history tab... From there, you can select locations and specific calendar dates to see the stats for each (or maybe you have to choose the location before you start... It's been a while since I used it) but that's how I decided what level of cold weather gear I should buy

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[DaveB]

Those web sites will give you historical averages and possibly the extremes.  They will tell you almost nothing about what will really happen while you are there.   

There is a saying called "The Traveler's Rule" which goes; "It will be hotter than you think, it will be colder than you think and it will rain more than you think." 

[Pat Lamb]

As Dave said.  Plan on a week of 100F, and it'll freeze at least once in the mountains of Colorado and Wyoming.

[jamawani]

Seat-of-the-pants weather knowledge is why us westerners have to rescue easterners all the time.

[walks.in2.trees]

Seat-of-the-pants weather knowledge is why us westerners have to rescue easterners all the time.

Seat of the pants is a short-term thing. You can't base gear for months worth of travel on tomorrow's weather at your own house. Especially not if you'll be in the mountains where things can change in a matter of hours. Most 3-season people plan for a 20° Low... I'm a 4-seasoner so my winter kit is 0°, overstuffed, and I bring my 50° summer kit to supplement it (it's supposed to be a 45°, but functionally it's 50°)  I don't wait for the temp to drop down to 0° though before I add my summer kit to it though, I add it on at around 20°, that way, if it drops under during the night, I don't wake up shivering, already having lost a lot of heat, try to put it all on while shivering then have to wait for my body warm up before I'm comfortable enough to sleep again.

As Dave said.  Plan on a week of 100F, and it'll freeze at least once in the mountains of Colorado and Wyoming.

Those web sites will give you historical averages and possibly the extremes.  They will tell you almost nothing about what will really happen while you are there.   

There is a saying called "The Traveler's Rule" which goes; "It will be hotter than you think, it will be colder than you think and it will rain more than you think."

only meant for LONG-TERM planning... that's why I said NOT to use the extremes... extremes are once or twice in a life-time events and extremes on the warm side don't matter for cold weather prep, while extremes towards the COLD side happen so rarely that it's overkill to bring gear for it everywhere...Plus, with global warming, those past extreme cold events are getting rarer anyway.  This doesn't mean that you shouldn't be aware of what the extremes have been or that they can't happen again, only that you don't want to base your everyday kit on it.

If you have to pick ONE setup, you err on the side of safety, or don't go at all... if you go anyway, thinking you can supplement with whatever else you bring, maybe it works and maybe it doesn't, however that works out, well, that's on you.

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[RussSeaton]

Leaving Virginia in early may and finishing in Seattle  beginning of july  what kind of low temperatures  should I be expecting.

May in Virginia, West Virginia, Ohio, Indiana you can easily get 40s at night.  Likely upper 40s.  June in Illinois, Missouri, Kansas, east Colorado expect lows of 50s likely.  Mountains, I'm not sure.  It can easily freeze in the mountains, but you are not going to camp at the high elevations where the freezing and possible snow will occur.  You will camp where it could get 40s maybe maybe 30s.  June, July west of the Rockies, expect lows of 40s or 50s.  To get the warmest weather, you should postpone your start date by one month.  You're a little bit early and could get cooler weather.  July and August are the hot months.  Not May and June.

[canalligators]

When I was prepping for a backpacking trip in New Mexico (Philmont), I was advised to be prepared for 35F and raining.  It sounds like that' what the OP was looking for - what does he need to be prepared for?  Couldn't someone just give the poster that kind of answer?  I don't think that's too much to ask, and it wasn't an unreasonable question.  Quite a good question, actually.

[John Nelson]

I'm not sure if you're asking to plan your camping, or to plan your riding. If for camping, you probably do not need to consider the weather on the passes, because you're not likely to camp on the passes. Anyway, I plan my clothing and camping choices to be the least that will keep me alive in the worst possible conditions. It's okay to be uncomfortable in unusual weather--you just don't want to die. I plan my clothing such that on the coldest night, I will be wearing everything I brought at the same time.

[staehpj1]

If for camping, you probably do not need to consider the weather on the passes, because you're not likely to camp on the passes. Anyway, I plan my clothing and camping choices to be the least that will keep me alive in the worst possible conditions. It's okay to be uncomfortable in unusual weather--you just don't want to die. I plan my clothing such that on the coldest night, I will be wearing everything I brought at the same time.

^ This except, I want a little better than not dying, I want to be sure of keeping all my fingers and toes

For the TA at that time of year, I'd expect frost at some point and to be over 100F at some point.  We did it an exceptionally hot year and 100F a lot of the way, but even on that trip we had some moderately cold nights (never much below 32 F).  One evening it was bitter cold and a howling wind on top of a pass, but we rode down into the next town and it was much warmer where we camped.

[DaveB]

May in Virginia, West Virginia, Ohio, Indiana you can easily get 40s at night.  Likely upper 40s.  June in Illinois, Missouri, Kansas, east Colorado expect lows of 50s likely. 

I can tell you from personal experience that overnight temperatures in the high 30's have occurred in mid-Ohio in mid-June.   

[Pat Lamb]

When I was prepping for a backpacking trip in New Mexico (Philmont), I was advised to be prepared for 35F and raining.  It sounds like that' what the OP was looking for - what does he need to be prepared for?  Couldn't someone just give the poster that kind of answer?  I don't think that's too much to ask, and it wasn't an unreasonable question.  Quite a good question, actually.

We may have scared him off -- you'd think he'd asked for the best chain lube by the passions the poor guy provoked.  But I agree it's a good question.

It's probably useful to be aware of the extremes for the week at a given location, but overkill to expect it.  A few years ago a late frost hit the last week in April and killed back all the trees; first time in over 100 years a local orchard produced nothing.  Would you expect it?  Only if you're gunning for the "most pessimistic" title.  Have a plan to deal with it?  Probably a good idea, either find a motel or put on all your clothes, hat, warm gloves, and shiver out the night.

Using the weatherspark.com data for instance, would it be better to plan for 75% high/25% low, or 90% high/10% low?  Forget the average -- the conflation with "normal" in the statistical sense of the average, and the usual sense of "normal" as what you'd expect, is egregious in the weatherman's patter.  On average, the temperature is not average.

[jamawani]

Given how easy it is to find climate normals online - in the 1980s, you could still get them, albeit in reference tomes at larger libraries - I find the resistance to baseline information difficult to understand.

Based on the thread here - much of the evidence is anecdotal. Things like - "It was really cold when I did the TransAm."  Or - "It was over 100 most of the time when I rode cross-country." Well, 2009 had one of the coolest summers in a long time and 1997 one of the hottest. And on any one day in any one month in any one year, there can be a wide range.

But looking at average highs, lows, and precip can give you core knowledge from which to work. Summer temp ranges are far great in the West than the East. It might be 95 in both Montana and Ohio, but it will only go down to 70 in Ohio while it may drop to 40 in Montana. Not to mention that the humidity will be much worse in Ohio. There may be one day in the summer where the humidity in Cincinnati is lower than the humidity in Helena, but it still does not change the basic fact that Montana has far lower summer humidity.

The biggest weather misconception that most easterners have about the West has to do with June. In the Northern Rockies you can still get snow well into June. It comes and goes fast, but a day or two can be nasty. Plus, there is still a lot of snow on the ground in June at higher elevations. Especially if it has been a snowy winter, it takes a long time for the snow to melt out - particularly on back roads and forest roads that are not plowed.

Climate normals are just that - long-term averages. However, I can assure you that over a multi-year period, you have a much better chance of having good weather if you start a tour in early May on the West coast in Sausalito than in Astoria.

[RussSeaton]

May in Virginia, West Virginia, Ohio, Indiana you can easily get 40s at night.  Likely upper 40s.  June in Illinois, Missouri, Kansas, east Colorado expect lows of 50s likely. 

I can tell you from personal experience that overnight temperatures in the high 30's have occurred in mid-Ohio in mid-June.

Yes.  If you look at the record temps for most places you will likely find highs of 100+ to lows of -50+ for almost everywhere.  It hit 70 degrees last week in mid Iowa.  I rode my bike.  Unfortunately, or fortunately, that is not the normal temp.  Your high 30s in mid Ohio in mid June is likely a once a decade event.  Not something I would use for planning a ride.  In mid June in mid Ohio the average low at night is probably 50-60.  Highs of 60-70.  Give or take 5-10 degrees either way.  I'd use that for planning.

And you are also forgetting the seasonal effect.  You always think things are colder than they really are in summer because you are used to hot weather.  And in the winter you think things are warmer than actual because you expect cold.  A friend stopped by yesterday on a bike ride.  He said it was 45 degrees or so.  I looked at my thermometer and he used an app to get the temp on his phone.  It was really 35.  I walked outside and it felt warm and pleasant but still cool.  I might have guessed it was 40 or so.  But it was only 35.  In February you expect cold weather.  3 degrees above freezing seems warm.