Southwest Gas Arizona Residential Gas Rates Per Therm Explained
- 01. Southwest Gas Arizona Residential Gas Rates Per Therm: Current 2026 Prices Explained
- 02. Current Southwest Gas Arizona Rate Breakdown
- 03. Recent Rate Changes and Historical Context
- 04. Seasonal Usage Patterns and Winter Bill Expectations
- 05. Low Income Ratepayer Assistance Program Discounts
- 06. Why Rates "Feel Off" to Customers
- 07. How to Calculate Your Exact Per-Therm Cost
- 08. Upcoming Rate Projections for 2026
- 09. Where to Find Official Rate Information
Southwest Gas Arizona Residential Gas Rates Per Therm: Current 2026 Prices Explained
Southwest Gas Arizona residential customers currently pay $0.36934 per therm for the Monthly Gas Cost (MGC) rate effective January 1, 2026, plus a delivery charge of $1.01138 per therm for single-family basic service, resulting in a total combined rate of approximately $1.38072 per therm. This represents a decrease from the previous MGC rate of $0.37836 per therm, providing meaningful bill relief for Arizona households heading into mid-2026.
Current Southwest Gas Arizona Rate Breakdown
The total gas bill consists of two primary components: the commodity cost (MGC) and the delivery charge. Understanding this distinction is critical for homeowners analyzing their monthly utility costs and comparing rates across utility providers in the Southwest region.
| Rate Component | Per Therm Cost | Monthly Service Charge | Effective Date |
|---|---|---|---|
| Monthly Gas Cost (MGC) | $0.36934 | N/A | January 1, 2026 |
| Delivery Charge (G-5 Single-Family) | $1.01138 | $10.70 | January 2023 |
| Total Combined Rate | $1.38072 | $10.70 | May 2026 |
| Low Income (G-10) Delivery | $0.54647 | $7.50 | January 2023 |
The Arizona Corporation Commission (ACC) approved these rates after Southwest Gas filed its most recent rate case application in March 2025. The delivery charge remains stable since the 2023 ACC ruling, while the MGC fluctuates monthly based on a 12-month rolling average of purchased natural gas costs.
Recent Rate Changes and Historical Context
Arizona residents have experienced significant rate volatility over the past three years. In March 2025, the ACC approved an $80 million revenue increase-33% less than Southwest Gas's original $126 million request-resulting in an average bill increase of $3.60 per month for single-family homes.
- March 28, 2025: ACC approves $80 million rate increase, raising average monthly bill from ~$47.00 to ~$51.00
- October 1, 2024: GCBA rate drops from $0.30911 to $0.00 per therm, saving average customers ~$7/month
- September 2024: Commission approved ~$1.87 monthly bill credit for average residential customers
- January 1, 2026: MGC rate decreases from $0.37836 to $0.36934 per therm
- January 2023: Base delivery rates approved following general rate case, setting G-5 at $1.01138/therm
This historical trajectory shows that while base delivery charges remain fixed, commodity costs create meaningful month-to-month variation in actual bills. Natural gas prices stabilized in recent years, resulting in an overcollection in Southwest Gas's Gas Cost Balancing Account.
Seasonal Usage Patterns and Winter Bill Expectations
Arizona homeowners who use natural gas for space heating typically see dramatically higher bills during winter months. On average, Southwest Gas residential customers pay approximately $67-$70.50 per month during winter, compared to significantly lower summer bills.
- Winter months (November-April): All usage charged at $1.01138 per therm delivery + MGC
- Summer months (May-October): First 15 therms at $1.01138/therm, over 15 therms at $0.16117/therm for G-15 special AC service
- Average annual usage: Single-family homes use approximately 24 therms per month annually
- Typical winter usage: Can exceed 29 therms per month for former GCU customers
The seasonal variation explains why many customers feel their rates "feel off" when comparing summer versus winter statements-the per-therm delivery charge is constant, but usage volume triples during heating season.
Low Income Ratepayer Assistance Program Discounts
Qualified low-income households receive substantial discounts through the LIRA program, which the ACC expanded to 250 percent of the federal poverty level. Eligible customers receive a 30% reduction on the per-therm rate year-round plus reduced monthly service charges.
| Service Class | Basic Service Charge | Delivery Charge per Therm | Eligibility |
|---|---|---|---|
| G-5 Single-Family (Standard) | $10.70 | $1.01138 | All customers |
| G-10 Single-Family Low Income | $7.50 | $0.54647 | ≤250% federal poverty |
| G-11 Multi-Family Low Income | $7.50 | $0.65922 | ≤250% federal poverty |
This discount program reduces the effective per-therm cost for low-income customers by approximately 46% compared to standard rates, providing critical relief for vulnerable households.
Why Rates "Feel Off" to Customers
Many Arizona residents report that Southwest Gas rates feel inconsistent because the bill structure separates commodity costs from delivery charges, making it difficult to track what portion reflects market volatility versus fixed utility costs.
The Monthly Gas Cost component changes monthly based on the 12-month rolling average, meaning customers see different per-therm commodity charges every billing cycle even if usage remains constant. Additionally, the Gas Cost Balancing Account adjustments create surprise credits or debits that appear separately on statements.
"Natural gas prices have stabilized in the last two years, resulting in an overcollection in SWG's GCBA balance," the Arizona Corporation Commission stated in its March 2025 decision.
This billing complexity leads customers to question whether rates are accurate when they compare month-to-month statements without accounting for the MGC adjustment mechanism.
How to Calculate Your Exact Per-Therm Cost
To determine your actual per-therm cost, add the current MGC rate to your specific delivery charge based on service class. For a typical single-family home in May 2026:
$$ \text{Total Rate} = \text{MGC} + \text{Delivery Charge} = \$0.36934 + \$1.01138 = \$1.38072 \text{ per therm} $$
For a household using 24 therms monthly (the annual average), the calculation looks like this:
- Gas commodity cost: 24 therms x $0.36934 = $8.86
- Delivery charge: 24 therms x $1.01138 = $24.27
- Basic service charge: $10.70
- Total monthly bill: $43.83 (excluding taxes and fees)
This sample calculation demonstrates why the average winter bill reaches $67-$70.50 when usage increases to 35-40 therms during cold months.
Upcoming Rate Projections for 2026
The $1.87 monthly bill credit approved in September 2024 is expected to last through April 2026, meaning customers may see adjustments beginning in May 2026 if the GCBA balance normalizes.
- Current MGC rate: $0.36934 per therm (effective January 1, 2026)
- Previous MGC rate: $0.37836 per therm (through December 2025)
- MGC decrease: $0.00902 per therm (2.4% reduction)
- Credit expiration: April 2026 for the $1.87 monthly credit
The commodity cost trend suggests rates may stabilize or increase slightly if natural gas futures rise, but current projections indicate continued relief through mid-2026 due to the overcollection in the balancing account.
Where to Find Official Rate Information
Customers should consult southwestgas.com or the Arizona Corporation Commission website for the most current rates, as the MGC changes monthly and base rates may be updated through formal rate cases. The utility's invested-in-Arizona page provides detailed rate schedules and adjustment notices.
For rate case documents, the ACC maintains public records of all Southwest Gas filings, including the March 2025 decision that approved the $80 million increase with 33% reduction from the original request. Customers can file inquiries directly through the Commission if they believe their bill contains errors.
Understanding the two-part rate structure-commodity cost plus delivery charge-is essential for Arizona residents managing household energy budgets, particularly as winter heating season approaches each year.
Everything you need to know about Southwest Gas Arizona Residential Gas Rates Per Therm Explained
What is the current Southwest Gas Arizona residential gas rate per therm in 2026?
The current total rate is approximately $1.38072 per therm, consisting of a $0.36934 MGC commodity charge and a $1.01138 delivery charge for single-familybasic service, effective January 1, 2026.
Why did my Southwest Gas bill increase even though rates decreased?
Bill increases typically result from higher winter usage volume rather than rate changes; average winter usage reaches 29-40 therms compared to 15-20 therms in summer, tripling the total cost even at lower per-therm rates.
How often does the Monthly Gas Cost (MGC) rate change?
The MGC rate updates monthly based on a 12-month rolling average of purchased natural gas costs, meaning customers see different commodity charges every billing cycle.
What is the Low Income Ratepayer Assistance (LIRA) discount?
The LIRA program provides a 30% reduction on the per-therm delivery rate year-round plus reduced monthly service charges for households at or below 250% of the federal poverty level.
When do Southwest Gas Arizona rates typically increase?
Rates typically rise during winter months (November-April) due to increased heating usage, while the Arizona Corporation Commission generally considers base rate cases in early-year proceedings like the March 2025 decision.
Is the $1.87 monthly bill credit permanent?
No, the $1.87 monthly bill credit for average residential customers is expected to last through April 2026, after which the GCBA balance may normalize and adjustments could occur.