Manual J design temperatures for Houston, TX
Winter 35.6 °F, summer 96.6 °F / 76.3 °F wet bulb, daily range M: the outdoor design conditions for a residential load calculation in Houston, with a free lookup for any address.
Houston, TX: Manual J outdoor design conditions
| Winter design dry bulb (99 %) | 35.6 °F |
| Summer design dry bulb (1 %) | 96.6 °F |
| Coincident wet bulb (1 %) | 76.3 °F |
| Daily range class | M |
| Grains difference (75 °F, 50 % RH indoor) | +40 gr/lb |
| Elevation | 226 ft |
ASHRAE Handbook method (2025 edition) at Houston-Dunn Heli (WMO 720594), 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 Houston
Heating equipment and heat pumps in Houston are sized for an outdoor temperature of 35.6 °F: colder than that for only about 88 hours in a typical year. Cooling is sized for 96.6 °F with a coincident wet bulb of 76.3 °F. The daily range is medium (15 to 25 °F), which sets the Manual J cooling-load factors, and a grains difference of +40 gr/lb drives the latent (moisture) load. With indoor design temperatures of 70 °F heating and 75 °F cooling, the design temperature differences are 34.4 °F and 21.6 °F.
Look up an exact address
Nearby cities
Austin · San Antonio · Dallas · New Orleans · Oklahoma City · Memphis · all 50 cities
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 Houston, TX?
35.6 °F: the 99 % heating dry bulb by the ASHRAE method at Houston-Dunn Heli.
What is the Manual J summer design temperature for Houston, TX?
96.6 °F dry bulb (1 %) with a coincident wet bulb of 76.3 °F.
Which daily range class does Houston 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.
Need the PDF for the file?
Free to try, no credit card.
Open the Manual J tool →