French Reference Grammar - Date, numbers and weather

Ordinal numbers (1st - 10th)

first - premier/premiere (can be abbreviated to '1er/1ère')

second - deuxième (2e)

third - troisième (3e)

fourth - quatrième (4e)

fifth - cinquième (5e)

seventh - septième (7e)

eighth - huitième (8e)

ninth - neuvième (9e)

tenth - dixième (10e)

Notes on numbers

• A hyphen is used between the numbers when they are used to build up in the teens, twenties etc, but not for 21, 31, 41, 51, 61 and 71. 
• In these numbers the word 'et' without hyphens joins the two numbers; thus: 'vingt et un', 'trente et un', 'quarante et un', 'cinquante et un', 'soixante et un' and 'soixante et onze'. 
• From 60, the numbers 1 to 19 are used to build up from 61 to 79, and from 80 they are used to build up from 81 to 99. 
• 'Quatre-vingts' is 80, and has a final 's' - just like 'four twenties'. 
• From then on, when 'quatre-vingt' is followed by another number in the building up process, there is no 's', nor is there an 'et' at 81 or 91. Thus, 'quatre-vingt-un', 'quatre-vingt-cing', 'quatre-vingt-dix', 'quatre-vingt-onze', 'quatre-vingt-douze'. 
• From 100, there is no hyphen or 'et' between the word 'cent' and the next number, but the previous rules still hold with the numbers used to build up from the hundred. Thus, 'cent', 'cent un', 'cent deux', 'cent dix-huit', 'cent quatre-vingt-dix-neuf'. 
• 200, 300, 400, etc have an 's' on the 'cent', thus 'deux cents', 'trois cents' etc, but there is no 's' if another number follows. Thus, 'deux cents', but 'deux cent un'. 
• 'Mille' meaning 'thousand' never has an 's'. Thus, 'deux mille'. If you add an 's' and write 'deux milles', it means 'two miles'.
• The ordinal number most likely to be needed is 'first', which is premier/première. It is used in dates.
• Relax: how often do you ever need to write the numbers out in full?