Data: 2023 USDA zones (PRISM/OSU) · NOAA 1991–2020 normals · updated

Planting zone for 77521 — Baytown, TX

ZIP code 77521 (Baytown, Harris County) is in USDA zone 9b: the coldest winter night averages 25 to 30 °F. The median last spring frost is February 20 and the first fall frost December 4.

Where ZIP 77521 is

Outlined: the ZIP code area · tap the map for the zone at any spot · scroll or pinch to zoom

Not the official USDA Plant Hardiness Zone Map. Zones come from the 2023 USDA hardiness-zone data by the PRISM Group, Oregon State University; we re-mapped and recolored them. The official map is at planthardiness.ars.usda.gov.

Zone9b25 to 30 °F
Coldest night−3.9 to −1.1 °C
Last frostFeb 20
First frostDec 4
2012 zone9a

Was 9a on the 2012 map — half a zone warmer now. The zone is the one at the center of the ZIP code; hilly ZIPs can span two zones. What zone 9b means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Baytown, TX…

Forecast data: National Weather Service (api.weather.gov), public domain. This is not a warning service — for official frost and freeze warnings see weather.gov.

Frost dates in Baytown, TX

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostFebruary 20median — 50% chance of a later frost
Safe for tender plantsMarch 14only 10% chance of frost after
First fall frostDecember 4median — 10% chance by Nov 12
Growing season292 daysfrost-free, median

A hard freeze (28 °F) usually ends around January 30 and returns around December 28.

From the NOAA station Baytown, TX — 7 miles away, elevation 26 ft. NOAA NCEI U.S. Climate Normals 1991–2020, 32 °F threshold. Low spots and valleys can freeze later in spring than the station.

When to plant vegetables in 77521

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Jan 9 – Jan 23
SpinachSow outdoors · Jan 9 – Jan 30
Broccoli, cabbageStart indoors · Dec 12 – Dec 26
Broccoli, cabbageTransplant · Jan 30 – Feb 13
Onion setsPlant outdoors · Jan 23 – Feb 6
PotatoesPlant outdoors · Jan 30 – Feb 13
LettuceSow outdoors · Jan 23 – Feb 6
Carrots, beetsSow outdoors · Jan 30 – Feb 13
TomatoesStart indoors · Dec 26 – Jan 9
TomatoesTransplant · Feb 27 – Mar 13
Peppers, eggplantStart indoors · Dec 12 – Dec 26
Peppers, eggplantTransplant · Mar 6 – Mar 20
BeansSow outdoors · Feb 27 – Mar 13
Sweet cornSow outdoors · Feb 27 – Mar 13
Cucumbers, squashSow outdoors · Feb 27 – Mar 13
Fall lettuce, spinachSow outdoors · Oct 9 – Oct 23
GarlicPlant cloves · Nov 20 – Dec 25
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Feb 20) and first fall frost (Dec 4) with the rules of thumb U.S. extension services publish. Cool-season crops take a light frost; warm-season crops do best once the soil is above about 60 °F.

When spring arrived in 2026

In 2026, spring leaf-out near 77521 came on Jan 10 — 13 days earlier than the 1991–2020 average (Jan 23).

JanFebMarAprMayJun

The Spring Index marks the day when accumulated warmth is enough for lilac and honeysuckle to leaf out — a widely used signal that the growing season has started. Source: USA National Phenology Network, www.usanpn.org — Spring Indices, first leaf, 2026 (data as of 2026-09-08) and 30-year average 1991–2020 (CC BY 4.0).

Soil in Baytown, TX

The soil mapped at the center of ZIP 77521 is League — clay, somewhat poorly drained.

TextureClayholds water and nutrients; slow to drain and warm up
pH5.4strongly acidic; most vegetables like 6.0–7.0
DrainageSomewhat poorly drainedconsider raised beds
Organic matter2.1%moderate
Hydrologic groupDwater soaks in very slowly
Farmland classprime farmlandUSDA classification

Map unit: League clay, 0 to 1 percent slopes.

Soil Survey Staff, Natural Resources Conservation Service, USDA. Soil Survey Geographic (SSURGO) Database, via Soil Data Access, accessed 2026-10-29. The soil at the center point of ZIP 77521; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Baytown, TX

Summer high92 °Faverage high, July
Winter low41 °Faverage low, January
Hot days84days a year at 90 °F or more
Freezing nights9nights a year at 32 °F or less
Growing degree days7,082base 50 °F — the season’s usable heat
Longest day14 h 04 mindaylight on June 21
Shortest day10 h 14 mindaylight on December 21
Onions to growShort-daysummer days stay under about 14 h 20 min, so long-day varieties won’t bulb
Precipitation64.7 inper year, rain and melted snow

Average high and low, by month

30°40°50°60°70°80°90°100°32 °FJanuary: average high 63 °F, low 41 °F 63°41° JanFebruary: average high 66 °F, low 45 °F 66°45° FebMarch: average high 72 °F, low 52 °F 72°52° MarApril: average high 78 °F, low 59 °F 78°59° AprMay: average high 84 °F, low 67 °F 84°67° MayJune: average high 89 °F, low 73 °F 89°73° JunJuly: average high 92 °F, low 75 °F 92°75° JulAugust: average high 92 °F, low 74 °F 92°74° AugSeptember: average high 89 °F, low 69 °F 89°69° SepOctober: average high 82 °F, low 60 °F 82°60° OctNovember: average high 71 °F, low 50 °F 71°50° NovDecember: average high 65 °F, low 44 °F 65°44° Dec

Precipitation by month inches

0″2″4″6″8″January: 4.85 in precipitation 4.8 JanFebruary: 3.78 in precipitation 3.8 FebMarch: 3.94 in precipitation 3.9 MarApril: 4.51 in precipitation 4.5 AprMay: 6.01 in precipitation 6.0 MayJune: 7.08 in precipitation 7.1 JunJuly: 5.49 in precipitation 5.5 JulAugust: 6.82 in precipitation 6.8 AugSeptember: 6.41 in precipitation 6.4 SepOctober: 6.13 in precipitation 6.1 OctNovember: 4.94 in precipitation 4.9 NovDecember: 4.77 in precipitation 4.8 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Baytown, TX (7 mi away); precipitation: Baytown, TX (7 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

All 8 nearest ZIP codes share zone 9b.

775229b
Baytown, TX · 5 mi
775629b
Highlands, TX · 6 mi
775209b
Baytown, TX · 6 mi
775809b
Mont Belvieu, TX · 6 mi
775239b
Baytown, TX · 7 mi
775309b
Channelview, TX · 9 mi
775329b
Crosby, TX · 10 mi
775719b
La Porte, TX · 10 mi

All 4 ZIP codes in Baytown → · Texas planting zones →

Questions about 77521

What planting zone is ZIP code 77521?

ZIP code 77521 (Baytown, TX) is in USDA hardiness zone 9b on the 2023 map: the coldest night of an average winter reaches 25 to 30 °F (−3.9 to −1.1 °C).

When is the last frost in Baytown, TX?

The median last spring frost (32 °F) near 77521 is February 20; after March 14 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Baytown station.

When is the first frost in Baytown, TX?

The median first fall frost near 77521 is December 4, giving a median frost-free growing season of 292 days.

When should I plant tomatoes in 77521?

Start tomato seeds indoors around Dec 26 – Jan 9 and set transplants outside around Feb 27 – Mar 13, one to three weeks after the median last frost.

How much rain and snow does 77521 get?

About 64.7 inches of precipitation a year (NOAA 1991–2020 normals, Baytown station).

How hot do summers get in Baytown, TX?

The average high peaks at 92 °F in July, with about 84 days a year at 90 °F or more.

What kind of soil does 77521 have?

The USDA soil survey maps League at the center of ZIP 77521: clay, somewhat poorly drained, pH about 5.4 (strongly acidic).

Did spring come early in Baytown, TX in 2026?

Spring leaf-out near 77521 came on Jan 10 in 2026, 13 days earlier than the 1991–2020 average (Jan 23), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Baytown, TX?

Short-day onions: the longest day near 77521 is 14 h 04 min, so summer days stay under about 14 h 20 min, so long-day varieties won’t bulb.

Did the zone for 77521 change?

Yes. The 2012 USDA map put 77521 in zone 9a; the 2023 map puts it in zone 9b. The newer map uses 1991–2020 data and more weather stations.