Americans showed some compassion for their bad-weather delivery people this winter

If you've ever seen a food delivery person laden with bags navigate their bike through the snow as you make a beeline for your warm, dry couch, you'll be glad to hear that many of us are thanking them for going the extra, frozen mile with a bigger tip than usual.

Food delivery site GrubHub has gathered its tipping data from the last few months and noticed a pleasing trend: People tend to tip more in extremely bad weather.

On the one hand, it's common courtesy. On the other, it's nice to hear that people are actually doing it.

Note that the average national tipping percentage during the winter is about 14% of the total delivery order.

GrubHub looked at three major cities that have recently come through some serious winter weather and found that major bad weather events corresponded with tipping spikes in the affected areas.

NYC

• Year-round average: 13.1%
• Average on 1/26/15, during a blizzard: 9% higher
• Usual winter average: 14.6%

Chicago

• Year-round average: 13.4%
• Average on 2/1/15, during a blizzard: 12% higher
• Usual winter average: 13.6%

Boston

• Year-round average: 13.4%
• Average on 2/2/15, during a blizzard: 6% higher
• Usual winter average: 13.5%

Need some guidance on best tipping practices? Here's what to tip in every situation.