The official National Weather Service forecast for Prosper — 33.2362°N, 96.8011°W, 21.6 miles from I-635. Forecasts here are written by NWS FWD, this county’s forecast office.
| Collin County | J | F | M | A | M | J | J | A | S | O | N | D | Year |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg high °F | 55 | 59 | 67 | 75 | 82 | 90 | 95 | 95 | 88 | 78 | 66 | 58 | 76 |
| Avg low °F | 34 | 38 | 46 | 53 | 62 | 71 | 74 | 74 | 66 | 55 | 45 | 37 | 55 |
| Precip in | 2.6 | 2.8 | 4.0 | 3.8 | 5.0 | 3.7 | 2.0 | 2.4 | 2.8 | 4.5 | 3.3 | 3.1 | 40.0 |
1996–2025 normals for Collin County — the climate division Prosper sits in. All-time county record high 109.4°F (2011-08-04); record low -0.6°F (2021-02-16). Source: NOAA / National Weather Service.