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Longmont Weather Forecast 6/29-30/2020

In Brief:

Heat is interrupted by a passing trough Tuesday/Wednesday to be replaced by days of above normal heat again with daily thunderstorm chances.

Forecast Discussion:

No large scale storms are in the offing, but there is a fair amount of (mainly) Pacific moisture in place across our region (Figure 1 in the gallery). Daily afternoon storms, forming in the mountains and wandering eastward, will be the rule.  For Tuesday/Wednesday, a trough passes the state (with most of the cold air aloft remaining north of Colorado (Figure 2)).  This will cool us to normal temperatures and enhance the afternoon storm chances a bit (green circle Figure 3). The fires in the southwest are are being brought under control so we are seeing much less smoke/haze around northern Colorado (Figure 4). Rainfall, according to the GFS, is very light and spotty over the next 5 days (Figure 5).

The Longer Range Forecast:

By Thursday, a ridge reestablishes itself over the West. By Saturday the entire nation is under a ridge coast to coast (Figure 6). We return to high temperatures in the mid 90'sF most days with afternoon storm chances (Figure 3).  Unfortunately, fire weather conditions will be elevated and these storms might produce some lightning sparked fires.

Independence Day:

We will have a big ridge over most of the U.S. for Independence Day with high in the lower 90'sF and a fair chance of an afternoon thunderstorm. Summer and typical 4th of July weather.


Mostly cloudy

Mostly cloudy


UV Index
0 Low
30.2 Rising
10 miles
53 °F
S 12.7 mph
17.3 mph
Wind Chill
75 °F


Mostly cloudy w/ t-storms


88 °F

Some sun, then clouds with a couple of showers and a thunderstorm around late this afternoon

Mostly cloudy w/ t-storms

Saturday Night

58 °F

A shower or thunderstorm in spots early this evening; otherwise, becoming partly cloudy



92 °F

Rather cloudy with a thunderstorm in spots in the afternoon

Partly cloudy w/ t-storms

Sunday Night

59 °F

A thunderstorm in spots early in the evening; otherwise, clear to partly cloudy

Mostly sunny


93 °F

Mostly sunny

Mostly clear

Monday Night

59 °F

Mainly clear

Partly sunny


96 °F

Hot with partial sunshine; caution advised if doing strenuous activities outside

Partly cloudy

Tuesday Night

60 °F

Partly cloudy

Partly sunny


97 °F

Partly sunny and very warm


Wednesday Night

58 °F


Sunrise and Sunset

11:37 AM
2:33 AM

Based on AccuWeather data