What the index is
For each city and trade we counted permits filed in each calendar month over the window (three years in most cities), divided by the average month, and scaled so that an average month is 100. A month at 150 saw half again as many filings as average; a month at 50 saw half as many. It is a measure of how busy the trade is at the permit counter. It is not a price index, not a wait-time index, and it does not know about weather in any particular year.
Busiest and quietest month by city and trade
Each cell is the busiest month and its index, then the quietest month and its index. Seattle's HVAC row is the City's "Furnace & Heating" permit type; its heat-pump trade is listed separately underneath.
| City | HVAC | Electrical | Solar | Roofing |
|---|---|---|---|---|
| Seattle | October 130 / August 87 | October 154 / March 84 | October 143 / February 70 | June 136 / November 51 |
| Seattle (heat pump) | June 130 / January 80 | |||
| Colorado Springs | July 134 / February 82 | July 156 / December 67 | October 180 / February 73 | October 191 / January 67 |
| Chicago | April 121 / December 77 | September 125 / December 79 | August 146 / February 70 | August 164 / January 36 |
| Orlando | August 112 / November 84 | July 114 / September 81 | October 130 / September 67 | March 125 / September 85 |
| Miami | July 122 / December 75 | April 116 / November 91 | September 142 / February 59 | October 111 / December 83 |
| Boulder | August 131 / February 72 | October 173 / May 80 | July 141 / December 68 | June 126 / December 52 |
| Anaheim | August 147 / February 71 | September 148 / November 68 | October 124 / July 72 | August 116 / December 78 |
| Elk Grove | July 160 / February 66 | July 118 / August 74 | October 182 / December 73 | April 141 / February 71 |
| Sugar Land | June 143 / December 64 | September 125 / October 71 | June 154 / October 45 | April 173 / January 50 |
| Palo Alto | July 125 / March 63 | May 117 / December 76 | October 158 / May 70 | September 129 / December 55 |
Permit counts behind each cell are on the city's compare page. The smallest trade in the table is Sugar Land solar at 320 permits over the window; the largest is Colorado Springs roofing at 23,508.
HVAC: the equipment fails when the weather turns
HVAC filings peak between June and August in eight of the ten cities, including July in Miami (122), July in Elk Grove (160), July in Colorado Springs (134). The exceptions are Chicago, which peaks in April (121), and Seattle's furnace and heating trade, which peaks in October (130); Seattle's "Heat Pump & AC" permits peak in June (130). The quietest months: December in Miami (75), February in Elk Grove (66), August for Seattle furnaces (87).
If your system still works and you are replacing it on your own schedule, Miami's December sees 75% of an average month's filings against 122% in July.
Electrical: September or October in half of these cities
Electrical permits peak in October in Seattle (154), October in Boulder (173), September in Anaheim (148), September in Chicago (125) and September in Sugar Land (125). Colorado Springs peaks in July (156) and Miami in April (116). The quiet month is spread across the year: March in Seattle (84), December in Colorado Springs (67), December in Chicago (79) and November in Miami (91).
Solar: October in six of ten cities
October is the solar peak in Seattle (143), Colorado Springs (180), Orlando (130), Anaheim (124), Elk Grove (182) and Palo Alto (158). Chicago peaks in August (146), Miami in September (142), Boulder in July (141) and Sugar Land in June (154). February is the quietest month in four cities: February in Seattle (70), February in Colorado Springs (73), February in Chicago (70) and February in Miami (59). We have not tested why; the file only has the dates.
Roofing: the widest swings
Roofing has the biggest gap between busy and quiet months of the four trades. Colorado Springs runs from 67 in January to 191 in October; Chicago from 36 in January to 164 in August; Sugar Land from 50 in January to 173 in April. Seattle's roofing trade, small at 633 permits, peaks in June (136) and is quietest in November (51). Orlando (85 to 125) and Miami (83 to 111) are flatter.
What a quiet month means for you
- Fewer jobs being started. In a month at index 60 the trade files 40% fewer permits than average. Chicago roofing in January runs at 36, about a fifth of its August level.
- Price: unknown. We have no price by month. The filed value on a permit is an estimate, and we have not tested whether it moves by month. If a page tells you a month is "10–15% cheaper" with no source, treat it as a guess.
What this does not tell you
The index is a three-year average, so a bad hail year or a cold snap is smoothed in. It counts filings, not completions. It says nothing about a specific firm's calendar. For that, pick the city and trade on the compare page, look at who has pulled permits in the last twelve months, and call three.
How we know this
Source: each city's open permit dataset (Seattle, Colorado Springs, Chicago, Orlando, Miami, Boulder, Anaheim, Elk Grove, Sugar Land, Palo Alto), window 2023-10 to 2026-09, snapshots 1 to 18 October 2026. The monthly index is the count of permits filed in each calendar month across the window, divided by the mean month, times 100. Trades are classified by us from the city's permit descriptions; Seattle's "Furnace & Heating" and "Heat Pump & AC" are the City's own permit types. No price data is used on this page and none is claimed.
Numbers come from City of Seattle (SDCI) building, trade and electrical permits on single-family and duplex homes (the city's open-data exports); Pikes Peak Regional Building Department permits inside Colorado Springs city limits; City of Chicago building permits (Chicago Data Portal); City of Orlando building permits for one- and two-family homes; City of Miami building permits (since 2014); City of Boulder construction permits; City of Anaheim Accela building permits on single-family homes and ADUs; City of Elk Grove TRAKiT building permits on single-family, duplex, mobile-home and ADU homes; City of Sugar Land building permits on homes (the city's EnerGov permit exports); City of Palo Alto Development Center building permits on single-family, duplex and ADU homes, data through October 18, 2026. Nobody paid to be on this page and nobody can.
See every Seattle electrician by their permit record →
See every Colorado Springs roofer by their permit record →
See every Miami HVAC contractor by their permit record →
See every Elk Grove solar installer by their permit record →
Questions
- Is the quiet month the cheapest month?
We do not know. The index measures how many permits were filed, not what anyone paid. We have no price data by month. A quiet month means fewer permits are being filed in that trade, which is the fact you can use.
- What does an index of 154 mean?
That month saw 54% more permits filed than the average month over the three-year window. An index of 84 means 16% fewer. The twelve months of a trade in a city average to 100.
- Why is the peak month for HVAC different in Seattle and Miami?
Seattle's "Furnace & Heating" trade peaks in October, at the start of the heating season; Seattle's separate "Heat Pump & AC" trade peaks in June. Miami's HVAC, which is mostly cooling, peaks in July.
- Is there a best time of year to replace my HVAC system?
If the old system lets you wait, aim for the quiet months, when the fewest jobs are filed. Seattle's furnace and heating permits fall to an index of 87 in August and peak in October; Miami's mostly-cooling HVAC permits are lowest in December and peak in July; Sacramento County's are lowest in November. A quiet month means fewer jobs filed, not a published lower price.
- Is roofing the most seasonal trade?
In the cities here it has the widest swings: Colorado Springs roofing runs from an index of 67 in January to 191 in October, and Chicago from 36 in January to 164 in August.
Build your own list
Every firm with that kind of permit on record. Pick what you value. The list moves.
Related guides
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- Heat pump vs furnace: what San Diego County homeowners filed
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