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Why is the Migration Moving Northeast?

Highlights: The Stop-and-Go Nature of Monarch Migration
The monarchs made a clear push into Oklahoma and Arkansas during the past week. A strong south wind blew on Saturday and that single day was responsible for the week's biggest push. Watch the animated migration map and you can see the jump.

The cause of last week's stop-and-go migration were two cold fronts with a short break in between, when a warm front and south winds allowed the monarchs to make some progress. You can see the location of Saturday's warm front and south winds on the maps to the right.

The migration entered only one new state last week. (Can you find it?) This illustrates how little the migration advanced; instead, the butterflies were filling in behind the migration's leading edge. Remember, our map shows where observers saw the first monarchs of spring. Following behind is a parade of monarchs, millions strong and at least 1,500 miles long. (Last Wednesday Estela Romero reported that there were still thousands of monarchs at one of the sanctuaries as you'll read below.)

• Explore this week's sightings from citizen scientists!
• Record your predictions! Where will the monarchs go next?

The orange arc on this map shows where monarchs would be now if they had spread equally in all directions. Why do they advance most quickly to the northeast at this time of year?

What effect do temperatures have on the pace and direction of migration? Here are migration and temperature maps over five years for you to compare. Take a look! Compare this year to past years.