July 22 (Reuters) - U.S. energy firms likely added an above-normal 35 billion cubic feet of natural gas into storage last week, according to the average estimate in a Reuters poll released on Wednesday.

The estimate compares with an injection of 27 bcf during the same week a year ago and an average increase for that week of 30 bcf over the past five years (2021-2025).

In the prior week ended July 10, energy firms added 41 bcf of gas into storage. USOILN=ECI

If correct, the forecast for the week ended July 17 would increase stockpiles to 3.059 trillion cubic feet. That would be about 0.4% below the same week a year ago and about 6.5% above the five-year average for the week.

The U.S. Energy Information Administration is scheduled to release its weekly storage report at 10:30 a.m. EDT (1430 GMT) on Thursday.

There were 99 total degree days (TDDs) last week, near the 30-year normal of 89 TDDs for the period, data from financial firm LSEG showed.

Total degree days measure the number of degrees a day's average temperature is above or below 65 degrees Fahrenheit (18 degrees Celsius) to estimate demand to cool or heat homes and businesses.

Reuters polled 10 analysts, whose estimates ranged from injections of 19 bcf to 39 bcf, with a median increase of 35 bcf.

Early estimates for the week ending July 24 ranged from injections of 19 bcf to 42 bcf, with an average increase of 34 bcf.

Those figures compare with an injection of 44 bcf during the same week last year and a five-year average increase of 26 bcf.

Following is a list of poll participants. All figures are in billion cubic feet:

Organization	Forecasts in bcf
Price Futures Group	19
DTN	29
Energy Aspects	32
C H Guernsey	34
LSEG	35
SMC Report	35
Schneider Electric	36
Energy Ventures Analysis	38
Gelber & Associates	38
Natural Gas Intelligence	39