US soybean prices rose for a second straight week, as excessive heat and dryness threaten to further erode crop yields in the Midwest.

Futures for November delivery, the first of the new crop, rose as much as 1.4% on Friday at the Chicago Board of Trade. The contract was headed for a 2.2% weekly gain as of 12:07 p.m. Eastern time.

Minimal rainfall is expected in the next seven days in much of the Midwest, according to a government outlook. That poses a risk to crops, which need precipitation after this week’s sweltering weather, CHS Hedging said in a note.

Export demand from China also lent support. US exporters reported on Friday a sale of 121,000 metric tons of soybeans to China, according to the US Department of Agriculture.

Read more: Corn Harvest Is in Trouble as US Heat Fuels More Damage.

Corn and soybeans are entering the last stretch of the growing season in the US, with the harvest typically kicking off around late September. The annual Pro Farmer Crop tour is due to issue a national production estimate Friday, after surveying fields across the Midwest.

Soybean pod counts in some states on the tour have been high, which is “comforting,” Paris-based adviser Agritel said in a note. “However, we have yet to see these pods fill up to get a true idea of yield potential,” it said.

Read more: Summary of US Pro Farmer Crop Tour After Day Three (Table)

Author: Megan Durisin and Gerson Freitas Jr.