When do monarchs migrate through Texas?

Monarchs cross Texas twice a year. In spring they arrive from Mexico in early March and move north through the state laying eggs on milkweed. In fall, Texas Parks and Wildlife describes two routes south: a central path about 300 miles wide from Wichita Falls to Eagle Pass, which monarchs enter “during the last days of September” and have mostly left “by early November,” and a second route along the coast, “from the third week of October to the middle of November.”¹

That is the whole state in one paragraph. Where you live inside it changes the dates, the plants and, on the coast, whether the monarchs leave at all.

The two fall flyways, in the agency’s words

Texas Parks and Wildlife’s monarch page: “One traverses Texas in a 300-mile wide path stretching from Wichita Falls to Eagle Pass. Monarchs enter the Texas portion of this flyway during the last days of September. By early November, most have passed through into Mexico.” And: “The second flyway is situated along the Texas coast and lasts roughly from the third week of October to the middle of November.”¹

Other institutions describe the same funnel from farther away. The U.S. Forest Service: “Eastern North American monarchs fly south using several flyways then merge into a single flyway in Central Texas.”² Monarch Watch: “Their flight pattern is shaped like a cone, as they come together and pass over the state of Texas on their way south.”³ Journey North, from the roosts people report: “monarchs follow two distinct flyways as they travel to Mexico, an Eastern Flyway and a Central Flyway. Only one flyway appears to lead directly to Mexico.”⁴ A 2015 article in Texas Parks and Wildlife’s Eye on Nature newsletter gives a landmark: “In Texas, the migratory corridor roughly corresponds to I35, give or take a couple hundred miles on either side.”⁵

The agency does not place cities on its 300-mile path, and we have no measured edges for it. On a map, Austin and San Antonio lie between the latitudes of Wichita Falls and Eagle Pass and east of a straight line between them. Dallas–Fort Worth sits on I-35, the line the 2015 article uses for the corridor, and well east of a straight line between the two towns, so the two descriptions place it differently. Houston sits on the coast, where the second flyway runs. That is our reading of the map, not the agency’s.¹⁵

Where the roosts are reported

Journey North publishes the overnight roosts people report. For fall 2025, the Texas roosts it named were at Wichita Falls, where an observer wrote that “monarchs are beginning to roost in the willow trees in singles, twos, and small groups”; at Mason, where an observer counted about 100 on 1 October; and at Abilene, where two observers counted about 500 and 150 on 9 October. Journey North had 17 Texas roost reports by 10 October, and none of the ones it named was in Austin, San Antonio, Dallas or Houston.⁶ Mason is in the Hill Country; Abilene and Wichita Falls are on the Rolling Plains, west and northwest of the big cities. It may be that the part of the migration where people count hundreds in one tree runs west of the metros; it may also be that people with open country report roosts and people in city yards report single butterflies. No source settles it.

Monarch Watch’s guideline, by latitude

Monarch Watch publishes a table of when “good numbers of monarchs should be observed at each latitude” in fall, with the caution that it is “a general guideline” and that “the migration record at specific locations for any given year may differ from this overall pattern.”⁷ The rows that cross Texas: 33 degrees north, 29 September to 11 October; 31 degrees, 4 to 16 October; 29 degrees, 10 to 22 October; 27 degrees, 15 to 27 October; 25 degrees, 20 October to 1 November.⁷ Dallas–Fort Worth sits close to the 33-degree row and San Antonio close to the 29-degree row, so those two cities can quote Monarch Watch’s numbers directly. Austin and Houston fall between rows, and the table has none for them.

Spring: the pass that lays the eggs

The spring pass is the one that matters for a yard, because it is the egg-laying one. Texas Parks and Wildlife: “Early each March overwintering monarchs begin arriving from their overwintering grounds in Mexico. Seeking emerging milkweeds, they move through Texas laying eggs before dying.”¹ Monarch Joint Venture: “In March, this generation begins the journey north into Texas and southern states, laying eggs and nectaring as they migrate and breed.”⁸ Their offspring, the first generation of the year, leave the southern states for the north “in approximately late April through May.”⁸

The dated records people sent to Journey North in spring 2025 show the pass moving through: at Montgomery, north of Houston, on 8 March a female “laid 12 eggs on this milkweed sprout over time”; at Driftwood, southwest of Austin, three eggs on 12 March; at Glen Rose, north of Austin, nine eggs “on small antelope horn milkweed sprouts” on 17 March.⁹ Small sprouts, in the first half of March, at three places between Houston and Fort Worth. Those records, with the agency’s statewide “they move through Texas laying eggs,” are why milkweed in central and east Texas has to be up by early March, and why the honest advice is to set out nursery plants the previous fall, with seed sown in fall for the years after; when to plant milkweed in Texas goes region by region.

Region by region

Central Texas: Austin and San Antonio. Both are near the eastern edge of the central path, by our reading of the map.¹ In Travis County the busiest fall weeks, in the sightings people have logged, have fallen between 15 October and 4 November in each of the last three years; the Austin calendar has the year-by-year record and the freeze dates. San Antonio is near 29 degrees north, where Monarch Watch’s guideline is 10 to 22 October; in the sightings people have logged for Bexar County, the busiest week across all years was about 22 to 28 October, at the end of that row.⁷¹⁰ In both cities the caterpillar records peak in April, with a smaller fall run: within 40 km of Austin, 112 caterpillar records in October against 398 in April; within 40 km of San Antonio, 79 against 301.¹⁰

North Texas: Dallas–Fort Worth. On the I-35 line of the 2015 article and east of a straight line from Wichita Falls to Eagle Pass, near 33 degrees north, where Monarch Watch’s guideline is 29 September to 11 October.⁵⁷ In the sightings, Dallas County’s busiest week was about 8 to 14 October and Tarrant County’s about 22 to 28 October; two neighboring counties two weeks apart is a reason not to print one date range for the metro yet.¹⁰ Fall egg-laying is documented here. A north Texas study found that “fall reproduction is a response to available host plants and its timing enables pupae to eclose in time for migration to winter roosts,” and that monarchs on the study site were most abundant three to four weeks before the main passage.¹¹ Within 40 km of Dallas, 141 caterpillar records in October against 234 in April.¹⁰

Houston and the upper coast. This is the coastal flyway, “from the third week of October to the middle of November.”¹ And some of the monarchs here don’t leave. The U.S. Fish and Wildlife Service: “There are also non-migratory monarchs that remain year-round at the southern end of their breeding range in North America, including in parts of Florida, the Gulf Coast and California.”¹² The Xerces Society: “In the continental U.S., resident populations occur in Florida, along the Gulf Coast, and in Southern California.”¹³ Within 40 km of Houston, caterpillars have been recorded in every month of the year, and 16 percent of all monarch records fall in December, January and February.¹⁰ So a “first arrival” date means little in Houston, and the question of tropical milkweed, which lets monarchs breed through a mild winter, is a live one along the whole coast and in far South Texas.¹⁴

South Texas. Butterflies and Moths of North America: monarchs “may breed all year in Florida, South Texas, and southeastern California.”¹⁵ Within 40 km of Corpus Christi, 20 percent of monarch records fall in December through February.¹⁰ Texas Parks and Wildlife’s milkweed guide records tropical milkweed as naturalized in Cameron and Hidalgo counties.¹⁶

Far West Texas: El Paso. The record is thin: 88 research-grade sightings within 40 km of El Paso from 2018 to 2025, most of them in September through November.¹⁰ No source we have assigns El Paso to the eastern or the western population. Monarchs do come through, in small numbers, and no guide can promise caterpillars there.

Most fall monarchs are not laying eggs

Monarch Joint Venture: “Most monarch butterflies that emerge after about mid August in the eastern U.S. enter reproductive diapause (do not reproduce) and begin to migrate south.”⁸ Most, not all; the October caterpillar counts above are real. What a fall yard can offer the migrating majority is flowers, from late September into November.¹

Where to report what you see

Texas Parks and Wildlife’s monarch page points to iNaturalist as a place to record sightings, and Journey North maps adult, egg, caterpillar and roost reports through the season; the migration map page links to both.¹¹⁰

The editions

The Austin edition is the first. San Antonio, Dallas–Fort Worth and Houston are in research, and each will get its own dates, weather station and plant list, because the facts above differ from city to city. The city finder tells you which of these applies to your ZIP.

Last changed September 24, 2026.