Evergreen Lisa Weightman has rallied strongly in brutal conditions to claim a top-20-finish in the women's marathon at the world athletics championships in Budapest.

The 44-year-old Victorian picked off a host of other runners in the second half of the race, eventually finishing 16th in a time of two hours 30 minutes 50 seconds.

If Weightman makes it to Paris next year, she will become the first Australian track and field athlete to compete at five Olympic Games.

But Saturday's marathon was only her second at a world championships, coming 14 years after her debut in Berlin.

"It was really tough out there, the conditions were quite brutal but I'm actually really happy with my performance," Weightman said.

"It wasn't a top-eight but it was top-16 and I equalled my place that I did at those championships long ago in 2009.

"It's great that so many years later I'm still able to perform."

As expected, African runners coped best in the heat.

Amane Beriso Shankule (2:24:23) and Gotytom Gebreslase claimed a one-two finish for Ethiopia and the bronze went to Morocco's Fatima Ezzahra Gardadi.

"After we got rid of the rest, then it was a battle with my tough teammates," Shankule said.

"Gebreslase is a strong athlete and she wanted to defend her title."

Australians Sarah Klein and Izzi Batt-Doyle were 41st and 43rd respectively.