Normally, average daily temperatures in Arcata through the whole of December is 7. You can expect a high of 13 with lows around 5 celsius. We have put some more information here:
| Month | Degrees Celsius |
|---|---|
| Temperature | 7 |
| High Temperature | 13 |
| Low Temperature | 5 |
Useful Links: Arcata Weather: Average Weather & Yearly Climate