While ZIP codes per se have no effect on pollen counts, weather in different areas can affect local pollen counts, as Pollen.com explains. Sites such as Pollen.com track local pollen counts and make the information known by mailing alerts sorted by ZIP code.
Pollen counts typically increase after a mild winter, since trees can begin pollinating earlier in the year. Late rains can increase pollen levels. Windy weather also distributes pollen more widely, especially if there's little rain. On the other hand, late freezes reduce pollen counts because they delay pollination. While rain temporarily washes pollen from the air, spring rains can increase pollen because they increase the growth of grass, according to Pollen.com.