Heart Rate Monitor - erratic reading

Not sure if anyone can advise at all but the last two runs I've been on I've had problems with my heart rate monitor not working - the first run I'd go from a ridiculously high to a ridiculously low heart rate and the second run it just seemed to range from 50 - 70 all the way through.

I was wondering if it was to do with the cold weather and if anything could be done to fix the problem?  I wrapped up really warm on both days.  Althoujgh the watch is about 2 years old the strap is only about 3 months old.

Thanks in advance.

Jo

Could be a low battery on either watch or strap - that's usually when i get erratic readings. Would have thought it more likely to be strap as LED display on watch tends to fade if battery low. 

Worth changing battery just to double check. Hope you resolve the problem.

Might be static from wearing layers...one of my winter tops causes this problem for me.

Check the chest transmitter is fitted snugly and is making good contact.

I had the same problem and tightening up the chest belt solved the issue.

Thanks for the responses.  Had another heart rate strap that I don't use as it's too large.  However I swapped the gadget/battery on the front and all fine now - so looks as if it was the battery.

Jo