Headwinds Slowing Migration
October 20, 2016 by Elizabeth Howard

The migration is moving southward slowly. Persistent south winds are holding the butterflies back. See what migration data predicts about the population.

Monarch Butterfly Migration

"After two cool days with north winds and no monarchs, the wind has turned again and is coming in from the southeast. The number of monarchs has steadily increased all day. They're nectaring seriously," reported Sandra Schwinn of Broken Arrow, OK on October, 14, 2016


Stop and Go
South winds have been holding the butterflies back. During most of October, a persistent weather pattern has remained in place. Cold fronts have been weak and have only twice dipped as far south as Texas. On only 4 of the last 19 days has the wind blown down from the north.

The pattern finally broke on October 12th. In the absence of headwinds butterflies moved across Texas in a clear pulse — including this remarkable report of an estimated 5,000 monarchs.

 "A steady stream flying overhead for roughly 20 minutes, then a slow trickle for the next 40 minutes. I counted for 10 minutes and was counting anywhere from 230 to 282 every two minutes. There were monarchs anywhere from 2 to roughly 15 meters off the ground." Christoval, TX October 13, 2016

"On the Woodridge Elementary playground on Friday afternoon, about 50 monarch butterflies were spotted flying approximately 10 feet above ground." San Antonio, TX October 14, 2016  

Looking Ahead
Tomorrow's forecast shows a 2-day break from south winds. Without the wind impeding their travels, monarchs should flood into Texas on Thursday and Friday.

Population Prediction?
The migration has been underway for two months. What does the data we've collected so far predict about the population?

Scientists will measure the population in Mexico in December 2016. This year's results will be released by March 2017.

This Week's Highlights

Wind, Weather and Monarch Butterfly Migration
Persistent Pattern
Monarch Butterfly Migration
Peak in Plano
Joan Strop-Adams
Monarch Butterfly Migration
Roost in San Angelo
Michael Lanty

Fall Monarch Butterfly Migration Graph

Population Prediction?

Letter from Estela
Meet the people in Mexico who will announce the monarchs' arrival at the overwintering region.

"We will keep alert to give you the great news when monarchs arrive to overwinter with us this season!" says Estela Romero

Watching and Waiting in Angangueo

Map: Location of monarch butterfly overwintering region in Mexico

Report Your Sightings
What to Report to Track Fall Migration Monarch Butterfly: Adult Sighted Monarch Butterfly: Egg or Larva Sighted
What to Report Adult Butterflies
map | list | animation
Eggs and Larvae
map | list
Monarch Butterfly Migration Map: Fall Roosts, Fall 2016 Monarch Butterfly Migration Map: Peak Migration Fall 2016 Monarch Butterfly Migration Data
Fall Roosts
map | list | archives | animation
Peak Migration
map | list | animation
Next Update October 27, 2016