Weather Expectations (Deserts → Sierras → Coast)

Big picture: You’ll cross hot deserts, cool high mountains, and the foggy Pacific coast. Expect swingy temps and microclimates—layers win.

Spring (Mar–May)

• Joshua Tree/Zion/Bryce/Grand Canyon (desert & high plateau):
  Days 18–28°C (65–82°F) lower deserts; nights 5–12°C (40–54°F).
  Bryce & Grand Canyon rims can be cold: nights -3–5°C (27–41°F); late snow possible.
• Sequoia/Yosemite (Sierra):
  Cool to mild; 8–20°C (46–68°F) days, cold nights. Snow can linger at elevation; some roads/trails open progressively.
• San Francisco/Monterey/Santa Maria (coast):
  Cool-mild days 13–18°C (55–64°F); breezy/fog at times.

Takeaway: Pack a warm layer and light rain shell; desert sun is already strong.

Summer (Jun–Aug)

• Joshua Tree/Death Valley/Page/Monument Valley:
  Very hot. Days 35–46°C (95–115°F) (Death Valley can exceed 49°C/120°F); warm nights 24–32°C (75–90°F).
• Zion/Grand Canyon/Bryce:
  Zion valley 30–38°C (86–100°F); Grand Canyon South Rim milder 20–30°C (68–86°F); Bryce coolest 18–27°C (64–81°F) with crisp nights.
• Sequoia/Yosemite:
  Pleasant–warm 20–30°C (68–86°F); cool evenings. Afternoon thunderstorms possible (especially July–Aug).
• SF/Monterey/Santa Maria:
  Marine layer/fog common; 15–21°C (59–70°F), breezy.

Takeaway: Start hikes early, carry 2L+ water, electrolytes, sun protection; keep a fleece for mountain/coast nights.

Autumn (Sep–Nov)

• Deserts & plateaus:
  Best combo of clear skies + easing heat. Days 20–32°C (68–90°F); cooler nights.
  Bryce/Grand Canyon rims trend cold by Nov; early snow flurries possible.
• Sequoia/Yosemite:
  Dry, golden; days 15–25°C (59–77°F) early, dropping to 8–18°C (46–64°F) by Nov. Nights cold.
• Coast:
  Often warmest & clearest in Sep–Oct: 17–23°C (63–73°F); light wind.

Takeaway: Prime hiking weather; still pack layers for mornings/evenings.

Winter (Dec–Feb)

• Joshua Tree/Monument Valley:
  Cool days 10–18°C (50–64°F); cold nights -2–6°C (28–43°F).
• Zion/Bryce/Grand Canyon rims:
  Cold; frequent sub-freezing nights. Bryce often below -7°C (19°F); snow/ice on trails.
• Sequoia/Yosemite:
  Snow likely at elevation; chain controls possible; many high trails/roads closed. Valley days 6–12°C (43–54°F).
• Coast:
  Cool, damp spells; 12–16°C (54–61°F) with showers.

Takeaway: Warm layers, beanie/gloves, microspikes (if hiking icy trails), and flexibility for weather-related changes.

Microclimate Notes by Stop

• Joshua Tree: Dry heat, intense UV; big day–night swing.
• Zion: Canyon traps heat; The Narrows = cold water year-round (neoprene socks helpful).
• Bryce Canyon (2,400–2,700 m / 8,000–9,000 ft): Coolest stop; thunderstorms in summer afternoons.
• Grand Canyon South Rim (2,100 m / 7,000 ft): Cool rim, hot inner canyon; pace water carefully.
• Death Valley: Extreme heat risk; minimal shade; follow guide timing strictly.
• Sequoia: Higher elevation; afternoon storms possible; temps drop fast after sunset.
• Yosemite: Spring runoff = big waterfalls + slick Mist Trail; summer storms possible p.m.
• San Francisco: Fog/wind (“June Gloom”/“Fogust”); always bring a windproof layer.
• Monterey/Santa Maria: Cool ocean breeze; mornings can be foggy, afternoons clearer.

Smart Packing for Weather Swings

• Always: sun hat, high-SPF sunscreen, sunglasses, hydration system (2L+) + electrolytes, light rain shell, warm mid-layer.
• Hot season: breathable long sleeves, neck gaiter, extra water capacity.
• Cold/shoulder seasons: fleece/puffy, beanie, gloves; trail traction for icy mornings (Bryce/GC/Sequoia/Yosemite).
• Footwear: broken-in trail shoes with grip; water shoes optional for The Narrows.

Bottom line: You’ll meet three climates in one trip—desert, mountain, coast. Dress like an onion (layers), hydrate like a pro, and you’re golden.