Manual J design temperatures for St. Louis, MO
Winter 12.9 °F, summer 92.8 °F / 76.1 °F wet bulb, daily range M: the outdoor design conditions for a residential load calculation in St. Louis, with a free lookup for any address.
St. Louis, MO: Manual J outdoor design conditions
| Winter design dry bulb (99 %) | 12.9 °F |
| Summer design dry bulb (1 %) | 92.8 °F |
| Coincident wet bulb (1 %) | 76.1 °F |
| Daily range class | M |
| Grains difference (75 °F, 50 % RH indoor) | +45 gr/lb |
| Elevation | 413 ft |
ASHRAE Handbook method (2025 edition) at Cahokia-St Louis Downtown Ap (WMO 725314), the nearest station with a recent record to the city centre. A different address in the area can use a different station: look it up below.
What these numbers mean for a house in St. Louis
Heating equipment and heat pumps in St. Louis are sized for an outdoor temperature of 12.9 °F: colder than that for only about 88 hours in a typical year. Cooling is sized for 92.8 °F with a coincident wet bulb of 76.1 °F. The daily range is medium (15 to 25 °F), which sets the Manual J cooling-load factors, and a grains difference of +45 gr/lb drives the latent (moisture) load. With indoor design temperatures of 70 °F heating and 75 °F cooling, the design temperature differences are 57.1 °F and 17.8 °F.
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For a whole-building energy model, the same site gets hourly EnergyPlus weather files (EPW) with design days: typical year, actual years and future climate.
Frequently asked questions
What is the Manual J winter design temperature for St. Louis, MO?
12.9 °F: the 99 % heating dry bulb by the ASHRAE method at Cahokia-St Louis Downtown Ap.
What is the Manual J summer design temperature for St. Louis, MO?
92.8 °F dry bulb (1 %) with a coincident wet bulb of 76.1 °F.
Which daily range class does St. Louis use?
Class M: medium (15 to 25 °F).
Can I get the values for my exact address?
Yes: type the address in the lookup on this page. A one-page PDF for the permit or rebate file costs 1 credit.
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