Mosquitoes usually start “coming out” when the weather warms and stays consistently around 50°F (about 10°C) , which is when eggs hatch and adults become active again.

When in the year do they appear?

  • In warmer climates (like the southern U.S., Gulf Coast, or Hawaii), mosquitoes can be present year‑round because it rarely gets cold enough to shut them down.
  • In temperate or northern areas , mosquitoes typically emerge in late winter or early spring (often February–May, depending on the region) and stick around through the fall , fading after the first hard frost.
  • Across much of the U.S., peak activity is usually the summer months (June–August) when it’s hot and humid.

What time of day are they most active?

  • Many common species are most active at dawn and dusk , when it’s cooler and less windy.
  • In shady, humid spots some species will bite during the day , and a few types (like Aedes mosquitoes) are known daytime biters.

How this looks by region (general pattern)

Region / Climate type| When mosquitoes “come out”| Notes
---|---|---
Warm, humid South (e.g., Florida, Gulf Coast)| Often as early as February , can last into November or year‑round| Larvae thrive in standing water in warm weather. 379
West Coast & milder South (e.g., parts of California, Texas)| Typically March–September| Long, drawn‑out season thanks to mild winters. 79
Northern continental (e.g., Midwest, upper Midwest, Michigan)| Usually late spring (April–May) into late summer or early fall| Strong peak in July–August. 57

Quick preventative tips

  • Eliminate standing water (buckets, saucers, bird baths, gutters, old tires) where mosquitoes lay eggs.
  • Use long sleeves, pants, and insect repellent (DEET, picaridin, or oil‑of‑lemon‑eucalyptus) during dawn and dusk , when most species are hunting.
  • In very warm or humid areas , treat mosquito control as a year‑round chore rather than a “summer problem.”

If you tell me your country or state (for example, “Texas” or “UK”), I can give a more precise “when do mosquitoes come out” window for your area.