Natural gas forwards prices were mostly higher for the period between June 8 and 11 as Nymex July futures strengthened on increasing power loads, but one Northeast point continued to weaken in the face of easing demand after this week’s heatwave.

New England’s Algonquin Gas Transmission Citygate, which has traded unusually low so far this summer thanks to mostly mild weather and a host of pipeline repairs in the Northeast, continued to weaken this week as temperatures in the region are forecast to fall back to seasonal levels after surging as much as 15 degrees above normal.

Algonquin July basis tumbled 16.6 cents between Monday and Thursday to reach minus 38.3 cents/MMBtu, according to NGI’s Forward Look. Fixed prices for July were down 4.6 cents to $2.442/MMBtu.

The slide at Algonquin comes as AccuWeather forecasts show Boston highs dropping back to the 70s during the weekend and remaining there for the better part of next week after hitting the upper 80s on June 10 and 11.

In Hartford, CT, daytime temperatures are expected to stall out at 69 by Monday after soaring to 89 on June 11, the weather agency projects.

The swings in demand are about the only constant when it comes to the weather going forward, as forecasters with NatGasWeather are expecting the variations to continue into the last week of June.

“Bigger picture, we don’t believe widespread prolonged heat will cover enough of the U.S. to seriously intimidate the nat gas markets,” the weather agency said.

The next period of focus will be on what happens to the ridge during the last week of June as the next series of weather systems tracking across southern Canada arrives, NatGasWeather said.

If high pressure over the northeastern U.S. cedes ground after June 24, cooler air will again spill across many northern U.S. cities, which would be bearish, the agency said. If it holds, a very warm southern, central, and eastern U.S. pattern can set up, but still with much more to prove.

With the drop in temperatures this week comes an expected drop in demand as well. Industry analyst Genscape expects demand to average around 1.84 Bcf/d next week, down from an average 2.11 Bcf/d for the period between June 8 and 12.

Cash prices at Algonquin were also considerably lower, plunging some 91 cents in Thursday trading for Friday’s gas day, NGI natural gas indexes show.

Forward prices remained weak further out the Algonquin curve, with the balance of summer (August-October) basis price shedding 8 cents between Monday and Thursday to reach minus 38.7 cents/MMBtu. The fixed price for the balance of summer picked up 3.8 cents to hit $2.49/MMBtu, a modest uptick when compared with the rest of the country, which climbed an average of 11.4 cents.

WIth the ongoing weakness at Algonquin, and recent strength in New York prices, July prices at the two Northeast market hubs continue to tighten.

At Transco zone 6-New York, July basis climbed 6.3 cents between Monday and Thursday to reach minus 55.1 cents/MMBtu, while the July fixed price jumped 18.3 cents to $2.274/MMBtu.

The hefty increase for Transco zone 6-NY July this week narrowed its discount to Algonquin to 16.8 cents, compared with 45 cents just one week ago.

Prices further out the Transco zone 6-NY curve were more in line with the rest of the country, with the balance of summer basis price ticking up just 1 cent for the week to minus 88.8 cents/MMBtu and the fixed price climbing 12.8 cents to $1.99/MMBtu.

Meanwhile, Transco on June 9 experienced a pipeline rupture on its Leidy Line B between Station 517 (Columbia County, PA) and Station 520 (Lycoming County, PA). Following the rupture, scheduled quantities at the Marc I MP 136.21, Barto M3602, and Barto II M3626 receipt points were to be reduced to zero capacity.

Prior to the rupture, receipts at Marc I averaged 455.8 MMcf/d over seven days, while Barto M3602 averaged 94.7 MMcf/d, according to Genscape.

Transco has implemented a new capacity constraint location, Leidy 517-10 Aggregate Receipt MP 138, to limit the aggregated receipts at Marc I, Barto, and Barto II and will allocate available capacity based on transportation contract priority.

The pipeline also noted that Leidy Line Aggregate Receipt MP 101.00 will be limited to 1,019 MMcf/d until further notice.

Outside of the listed points, impacts to the pipeline have been minimal, Genscape said, with flows through Station 517 appearing unchanged and Station 520 experiencing a net backhaul.

Forward prices across the rest of the country posted double-digit gains for the week, mirroring the overall strength in the Nymex.

The July contract was up 18.6 cents between Monday and Wednesday, but fell 6.6 cents Thursday following a storage report that was mostly in line with expectations. The prompt-month contract continued to retreat slightly Friday.

Pacific Gas & Electric citygates had the highest fixed price for July, coming in at $3.193/MMBtu as power burn in the region has soared this week thanks to well above-average temperatures.

The lowest fixed price for July was recorded at Dominion South point, coming in at $1.451/MMBtu as rampant production in the region continues.