Nouns ending in a consonant followed by -y change the -y to -ies in the plural form.
Humidity is regular. It follows the -ies Conversion rule.
Use plural verbs: "The humidities are ready" (not "is ready").
Yes. The plural humidities is standard across all English variants.
The word humidity follows the standard English pluralization rule. When forming the plural, humidity becomes humidities. This follows the -ies Conversion pattern, which is one of the most common plural rules in English.
Understanding why humidity becomes humidities helps with spelling and pronunciation. Nouns ending in a consonant followed by -y change the -y to -ies in the plural form.
When using humidities in writing, remember that it functions as a plural noun in sentences. It pairs with plural verbs and pronouns. For example: "The humidities are ready" (not "is ready"). This subject-verb agreement is essential for grammatical correctness.