Cold Weather IM Prep.

I too am from So Cal, and I'll be there at IMAZ.  Here's my plan (based in part on 2010 St. George IM) and assuming you're not concerned about qualifying/podium.  St. George started off COLD in the morning, got warm, then cold and windy when sun went down.  And, disclaimer, I don't generally get really cold when training and racing, even if the weather is nasty.  If I'm riding/running, I'm generally warm, even in rain and wind. 

Plan on a full change in T1.  Change into dry tri shorts and top.  And, take the 1 minute hit to towel down fully and get the water off your body. 

Invest in arm warmers.  Early morning rides, even in SoCal (my home) are cold in the winter, so they are a good $30 investment.  I'd not recommend a long sleeve jersey.  If you find yourself warming up, there's nowhere to go at that point but bake, or to unzpip the front, and you're a parachute at that point.  You can always take off the arm warmers and either slide them onto your aero bars or jam them in your jersey pockets. 

Even then, with the arm warmers, plan to be cold at the start of the ride.  My teeth were chattering for the first 20 minutes at IMSG on the bike, and I didn't get warm until the end of the first climb out of Sand Hollow.  If you're riding hard, you should be sweating and warm in the first 20-30 minutes, max.  But frankly, unless you are very sensitive to cold, just plan to be cold for a little bit off the bike. 

As for the run, in my experinece, if you're running, your warm.  If you're walking, you're going to get cold.  Even if the afternoon is 70 and party sunny like they are forecasting, if you are forced to walk your body temp is going to drop and you are going to be cold.   My plan is to put a long-sleeve running/tech shirt in my T2 bag, and another, rattier one that I don't mind losing in my SN bag.  If I'm cold off the bike, or for whatever reason am questioning my ability to run off the bike, I'll take the one in T2.  If not, I'll leave it there and re-evaluate at the half way mark.  I can't imagine running with a rain jacket on.  I think I'd just bake if I were actually running.

If in doubt, take the long sleeve tops in T2, and you can tie them around your waist.

You could buy tube socks or soccer socks and cut the foot off and use them as disposable arm warmers.

I don't like be cold and last two IMs it has been in 40s and 50s on start of bike with high of low 60s last year and low 70s this year. If it is in the 40s or 50s for a couple hours I can't just wait for it to warm up especially if I'm cold out of the swim.

Another trick is to put up gallon ziplock up your jersey and it works similar to vest but cheap and you can dispose of it when you warm up.

Do you ride in similar temps? If so trust what has worked for you in past rides.

I'll be wearing my tri top and shorts for the entire race regardless of the weather.   I'll put arm warmers on in T1.  I'll also put a long sleeve top in my run special needs if I need it as the sun goes down.  If it stays cool on the bike then I'll leave the arm warmers on for the run.  No jacket for me as if it's raining hard enough to warrant one, it's not going to do much anyways....and if it is raining it will probably be windy, in which case I don't want the aero drag of a jacket slowing me down.

I did this in CdA this year where the water was 55 degrees and the air was in the high 50's when I got out of the water.   The arm warmers were all I needed to get warmed up....the tri top/shorts dried out really fast.  Ended up ditching the arm warmers once it warmed up.  

I've seen at cold weather cycling races where they hand riders sheets of newspapers to put under their jersey.  This blocks the wind and keeps them warm.  And when you dispose of it, it's biodegradable  

I run long during the cold winter months here in New York, and one thing I can suggest is: Do Not neglect your liquid and salt intake.  I've found on cold runs, my internal thirst mechanism does not work.  And when I realize it, it's often too late.  I would recommend closely focusing on your fluid intake schedule/ as well as electrolytes-salts.  Perhaps set your watch to beep every 15 mins for a sip of fluid, or something along those lines.  Of course you won't need as much fluid as you would on a hot or warm day, but I find I easily can go an hour without drinking in cool temps which is really bad during a long course event. 

As for the arm warmers, I have these pair of Asics arm warmers.  For 10 bucks, you can't go wrong.  And if you get hot, you just roll 'em down and they become wristbands; or you can easily stuff them in a pocket. 

It doesn't look like it's going to be very cold:

Day	Night
Few Showers High 69°F Precip 30% Wind: From SSW at 8 mph Humidity: 51% UV Index: 4 Moderate   Sunrise: 7:04 AM MT Avg. High: 76°F Record High: 89°F (2006)	Mostly Clear Overnight Low 53°F Precip 10% Wind: From SE at 4 mph Humidity: 39%       Sunset: 5:23 PM MT Avg. Low: 43°F Record Low: 23°F (1956)