beautiful, excellent, fair, fine, glorious, good, great, ideal, lovely, nice, perfect, superb (esp. BrE)
adverse, appalling (esp. BrE), atrocious, awful, bad, dismal, dreadful (esp. BrE), foul, gloomy, grim (esp. BrE), horrible (esp. AmE), inclement, lousy, miserable, nasty, poor, rotten, rough, terrible
hot, humid, muggy, sultry, warm
mild
bright, clear, sunny
calm
dry
reliable (esp. BrE), settled (BrE)
changeable (esp. BrE), fickle, uncertain, unpredictable, unsettled
extreme, fierce, harsh, severe, violent, wild
bitter, chilly, cold, freezing, frosty (esp. BrE), icy, wintry
cool
cloudy, grey/gray
damp, rainy, wet
foggy
blustery, stormy, windy
autumn (esp. BrE), fall (AmE), spring, summer, winter
unseasonable, unseasonably …, unseasonal (esp. BrE)
a spell of unseasonably warm weather.

local

spell

enjoy
I've been enjoying this beautiful weather.

have
We've had great weather all week.

brave
Deciding to brave the weather, he grabbed his umbrella and went out.

forecast, predict
check
I checked the weather this morning.

clear, clear up, improve, warm up
We'll go just as soon as this weather lets up.

hold, hold out (BrE), hold up, keep up
If the weather holds out we could go swimming later.

threaten
Bad weather threatened.

break, deteriorate, worsen
It was sunny until the weekend, but then the weather broke.

become sth, get sth, turn sth
Next day the weather turned cold.

look sth
The weather looks beautiful today.

remain sth, stay sth
continue
close in (esp. BrE), set in
The weather closed in and the climbers had to take shelter.
I wanted to mend the roof before the cold weather set in.

come
According to the forecast, there is a lot more wet weather to come.

allow, permit
I sat outside as often as the weather allowed.
We're having a barbecue next Saturday, weather permitting.

prevent sth
Stormy weather prevented any play in today's tennis.

let sb down (BrE)
change
bring sth out
The fine weather brings out butterflies.

conditions
The plane crashed into the sea in adverse weather conditions.

patterns, system
the effects of global warming on the world's weather patterns
Atlantic weather systems

forecast, report
data, information, records
event
an increase in extreme weather events

satellite, station
centre/center
chart, map

a change in the weather
We hadn't bargained for such a dramatic change in the weather.

in all weather (esp. AmE), in all weather conditions, in all weathers (BrE), whatever the weather
The lifeboat crews go out in all weather(s).
He swims in the sea every day, whatever the weather.

the vagaries of the weather (BrE), the vagaries of weather (AmE)
She packed to cope with the vagaries of New York's weather.