Higher easy run heart rate in cold weather

Have not noticed that, other than potential issues at the beginning of a run. Without a chest strap, often my HR is low the first five minutes when cold because the watch is not reading well (less blood at the surface of the skin). With a chest strap, sometimes when it's cold and dry my HR jumps up and down the first five minutes until I start sweating, if I don't pre-wet the sensors (due to static electricity - even with the sensors wet, some shirts can continue to cause static electricity issues when it's very dry, until sweat begins to dampen the material).

I’m not sure about a likely effect of cold temperature but:

Have you looked at enough data to have a pretty solid apples-to-apples comparison, so that you’ve accounted for a number of other factors (either by stratifying samples or by looking at averages over enough time and with enough similarity — similar variety — for some other factors to more or less cancel each other out), so that you are therefore largely comparing only one the basis of one temperature versus another?

Probably more that your watch or heart rate monitor doesn't work as well in the cold.

Is your footing identical? I'm dealing with snow and even when trails are fairly cleared, will slow me down 15-30s per mile. So if I try and maintain the same pace my HR is that much higher. Otherwise I might see a VERY marginal increase because of layering, but not anywhere near what you're describing.

Does it say in that range throughout the run? I do notice sometimes my HR will drop after a few miles when I've finally warmed up and loosen up in really cold weather.

did you feel ill at all? would you have noticed the slight uptick if you weren't reviewing data?

Have had this issue too. Could be that the watch is having issues if you aren't using a chest/arm strap. I generally notice lower heart rate in cooler weather, even if it's pretty cold out. Sometimes people are in their offseason around now & might be in slightly worse shape.

Could be cold gear is actually making you hotter in your core, while extremities and face still feel cold so you don’t notice as well.

Could be footing or pants that restrain range of motion and make you work harder for the same pace.

Could be it’s cold and you’re not breathing as freely or as fast.

You might be wearing too many layers? I feel like this has happened to me before and typically it's when I am wearing too many layers on a cold day.

If you are just using a wrist strap HR monitor, I would stop trying to go by the numbers. Just go by how heavy you are breathing and how difficult it feels. If you are having trouble singing to yourself as you run, slow down a little.
MAF is really just a label for a concept that has been around for a long time in running - Run easy paced for the majority of your runs. 32 degrees F is actually pretty good for keeping breathing and HR low, just wait till a hot and humid summer hits, it is quite depressing how hard it gets.

Stress on the body is greater in hot and cold weather. Your circulatory system will work to keep your extremities warm in cold. This seems perfectly normal. Do people expect to do intervals the same pace at 20F as the do at 50F or 90F? Not likely. That is why marathon WRs are run when the temps are 40-50F and not when the temp is 20F or 80F. Common sense.

I'd agree with this. Body temperature is higher and sometimes a lot higher with extra layers of clothing on and the heart rate acts accordingly.

I think this makes sense. There's an optimal temperature for running and your body will be under more stress the further you go from this. Therefore staying at the same pace your heart rate will be higher. Twenty five or below is pretty cold (presuming this is Fahrenheit). Would be interesting to see what your heart rate is at high temps. Also wonder what the best temp for least strain on your body/lowest heart rate is. Maybe around 15C?

(Not talking about a marathon which is at the more extreme ends, but just for casual running.)