Garden Climate for Guatay, CA 91931

Zone 8b · Last frost ~Apr 19 · Soil 60.3°F today (modeled) · See your place on the 2023 USDA zone map

This ZIP is part of Guatay & Pine Valley, where nearby ZIPs share the same stations and zone. That page compares every ZIP in the area.

Public NOAA/USDA data, updated 2026-10-16 19:24 UTC.

USDA Plant Hardiness Zone Map · Guatay focus

2023 USDA Plant Hardiness Zone Map around ZIP 91931, marker at Guatay, CA
7a7b8a8b9a9b10a10b11a

USDA Plant Hardiness Zone Map, 2023. Agricultural Research Service, U.S. Department of Agriculture. Accessed from https://planthardiness.ars.usda.gov/. Rendered unaltered from the PRISM Group, Oregon State University GIS data (https://prism.oregonstate.edu, accessed 15 Oct 2026) with official zone colors. Roads (TIGER/Line 2023 primary roads), place names (2023 Gazetteer) and state lines (2023 cartographic boundaries 1:500k) are drawn on top. Source: U.S. Census Bureau.

Zone
8b
USDA 2023 · 15 to 20°F
Last frost
Apr 19
avg last frost (50%)
Soil temp Modeled
60.3°F
↓ 9.8° in 7 days
Chill hours
—
unavailable
Rain
—
since Oct 1 · not enough data

Frost dates for 91931

Last spring frost
Apr 19
50% odds
First fall frost
Oct 27
50% odds
Safer spring date
May 14
10% chance of later frost
Growing season
190
days (50%)

Earliest-risk fall date (10%): Oct 9.

NOAA NCEI U.S. Climate Normals 1991-2020, annual/seasonal freeze probabilities (32F) · CA CUYAMACA HCN (USC00042239) 15.8 km away 25 yrs of record · 633 ft higher than this ZIP

Newsletter · 91931

Frost alerts and planting reminders for 91931. Coming soon.

Ad strip · leaderboard 970×90 / 728×90

7-day forecast · High / Low / Rain / Frost / Wind

High wind: 2 day(s) with gusts ≥40 mph. Stake and protect transplants.
Fri 16
69° 56° gust 53 mph 💧9%
High wind
Sat 17
65° 52° gust 43 mph 💧8%
High wind
Sun 18
68° 53° gust 17 mph 💧0%
Clear
Mon 19
69° 49° gust 16 mph 💧3%
Clear
Tue 20
59° 46° gust 28 mph 💧57% · 0.02″
Rain
Wed 21
54° 43° gust 24 mph 💧70% · 0.59″
Rain
Thu 22
55° 42° gust 21 mph 💧28% · 0.10″
Clear

NOAA NWS api.weather.gov (SGX). Frost = low ≤32°F · High wind = gust ≥40 mph · 💧 = chance of precipitation and expected amount (NWS quantitative precipitation forecast; blank when NWS gives none) · Rain = chance ≥50%.

What to grow when · 91931

Calendar: San Diego County, mountains (900 m / ~3,000 ft and up). Planting months from University of Arizona Cooperative Extension Yavapai County Bulletin #51 'Yavapai County Vegetable Planting Dates' (an out-of-county analog; no San Diego-specific guide covers this area). Harvest months add typical days-to-harvest. This month also checks live soil temperature and the 7-day frost forecast. The harvest planner uses the same calendar. Rules: methodology.

Affiliate links (disclosed). Placeholders, no partners yet:Frost clothSoil thermometer

Questions about 91931

What USDA hardiness zone is 91931?

ZIP 91931 (Guatay, CA) is in USDA zone 8b (15 to 20°F average annual extreme minimum), per the 2023 USDA Plant Hardiness Zone Map.

When is the last frost in 91931?

Based on NOAA 1991–2020 normals at Ca Cuyamaca Hcn (15.8 km away), the median last 32°F freeze is Apr 19. In 1 of 10 years it is after May 14. The median first fall freeze is Oct 27.

Nearby ZIP codes

91962 Pine Valley 91916 Descanso 91948 Mount Laguna 91901 Alpine 91963 Potrero 91906 Campo

Sources for this page

  • Location: US Census Bureau 2023 Gazetteer, ZCTA internal point
  • Zone: USDA Plant Hardiness Zone Map 2023, ZIP datasets (USDA ARS + PRISM Climate Group, Oregon State University)
  • Frost: NOAA NCEI U.S. Climate Normals 1991-2020, annual/seasonal freeze probabilities (32F) CA CUYAMACA HCN (USC00042239) 15.8 km away 25 yrs of record · 633 ft higher than this ZIP
  • Forecast: NOAA National Weather Service api.weather.gov (7-day forecast + gridpoint wind gusts)
  • Soil: Open-Meteo forecast API soil model (non-commercial terms)
  • Chill: RuntimeError: not enough nearby data: no suitable hourly weather station within 25 km
  • Raw data: /data/zip/91931.json