Natural gas futures were sharply higher during U.S. morning hours on Wednesday, re-approaching a 20-month high as investors looked ahead to Thursday’s closely-watched U.S. supply data.

On the New York Mercantile Exchange, natural gas futures for delivery in May traded at USD4.138 per million British thermal units during U.S. morning trade, up 3% on the day.       

Nymex gas prices rose by as much as 3.2% earlier in the day to hit a session high of USD4.144 per million British thermal units. The May contract rallied to USD4.177 per million British thermal units on April 8.

Early withdrawal estimates range from 20 billion cubic feet to 36 billion cubic feet. Inventories increased by 11 billion cubic feet in the same week a year earlier, while the five-year average change for the week is a build of 15 billion cubic feet.

Total U.S. natural gas in storage stood at 1.687 trillion cubic feet as of last week, 32% lower than last year at this time and 2.1% below the five-year average.

Gas inventories had held above the five-year average since September 2011.

Nymex gas prices have risen sharply in recent weeks, gaining almost 25% since mid-February, boosted by calls for colder temperatures in major consuming regions across the U.S. that helped tighten the market.

Still, some analysts have warned that further gains may be limited with spring’s low-demand shoulder season looming.

The heating season from November through March is the peak demand period for U.S. gas consumption. Nearly 50% of all U.S. households use gas for heating.

Gas use typically hits a seasonal low with spring’s mild temperatures, before warmer weather increases demand for gas-fired electricity generation to power air conditioning.