Laramie
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Laramie clear sky chart from 2005-11-06 to 2025-10-19.

This page is a summary of past forecasts. Even though it's based only on forecasts, some people use these pages as clue to a site's climate. But climate data based on actual observation should be preferred (if you can find it!).

Cloud, Transparency and Seeing forecasts are summarized individually. But because good observing conditions require a combination of minimum cloud cover, transparency and seeing, the individual forecast summaries can be difficult to interpret. The observing conditions section counts the combinations of conditions needed for common types of astronomical observation.

Observing Conditions

The following tables count the occurrence of the combinations of forecast and darkness conditions needed for different observations. Conditions are rated by by what percentage of the hours the observation would likely be attempted are usable.

Observation Type	Minimum conditions for hour to be usable				Out of hours
	Clear of Clouds	Transparency	Seeing	Sky Brightness
Planetary:	50%	(no limit)	Average	(no limit)	Nighttime Hours
Deep Sky:	70%	Average	(no limit)	5.9	Nighttime Hours
CCD Imaging:	70%	Below Average	Poor	(no limit)	Nighttime Hours

Percentages are of nighttime hours per month, or per year, when a particular observing conditions was met. Deep Sky percentages never exceed 50% because the moon is up half the time. Deep sky percentages are much lower for charts at high latitudes because of fewer dark hours in the summer.

Overall

By Month

Individual Forecasts

The length of each colored bar in the "occurrence of each Forecast" column is proportional to the number of times the chart forecast that color. The percentages are of the total number of hours per month, or per year, with a particular forecast. The colors as the same as those used in clear sky charts.

Note: Transparency probabilities are only counted for those hours that have 30% or less cloud cover. Seeing probabilities are only counted for those hours that have 80% or less cloud cover. If that's too tricky, try Observing Conditions instead.

Overall

		Occurrence of each Forecast	Data Points
Cloud Cover	Day	3 6% 3 7% 5% 4 5% 4 6% 7% 50%	135605
	Night	3 6% 3 6% 4 4 4 3 5% 8% 54%	131556
Transparency	Day	30% 7% 11% 24% 20% 8%	130506
	Night	27% 6% 13% 28% 20% 6%	127658
Seeing	Day	10% 21% 33% 23% 11% 2	17025
	Night	7% 21% 36% 26% 9% 1	26978

By Month

Percentage Cloud Cover SW (2006-)
Color Meanings: Overcast 90% covered 80% covered 70% covered 60% covered 50% covered 40% covered 30% covered 20% covered 10% covered Clear
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	6% 4 10% 8% 5% 4 4 6% 6% 48%	3638
	11th to 20th	Day	9% 5% 14% 8% 5% 4 3 4 6% 41%	3667
	21st to end	Day	1 4 3 10% 5% 3 4 3 4 6% 58%	4510
February	1st to 10th	Day	2 8% 3 9% 7% 5% 4 4 6% 8% 45%	1800
	11th to 20th	Day	1 8% 4 9% 5% 5% 4 3 7% 9% 45%	1858
	21st to end	Day	1 7% 4 7% 4 4 3 3 6% 8% 53%	1650
March	1st to 10th	Day	2 10% 4 8% 4 3 4 3 5% 6% 51%	4500
	11th to 20th	Day	2 10% 4 7% 4 4 4 4 6% 8% 46%	4996
	21st to end	Day	3 9% 3 9% 6% 5% 5% 4 6% 8% 41%	5782
April	1st to 10th	Day	4 11% 3 7% 4 4 4 4 6% 7% 45%	2400
	11th to 20th	Day	7% 13% 4 8% 5% 5% 5% 4 6% 7% 37%	2371
	21st to end	Day	7% 11% 3 7% 5% 5% 5% 5% 7% 7% 39%	2400
May	1st to 10th	Day	5% 12% 3 8% 5% 5% 6% 4 6% 6% 40%	6014
	11th to 20th	Day	7% 8% 2 7% 4 6% 6% 4 7% 8% 41%	6298
	21st to end	Day	5% 6% 2 6% 5% 5% 6% 5% 6% 8% 46%	6925
June	1st to 10th	Day	5% 5% 1 5% 5% 4 6% 5% 8% 9% 46%	2800
	11th to 20th	Day	6% 4 2 4 4 4 6% 5% 7% 8% 50%	2800
	21st to end	Day	3 3 2 5% 4 4 5% 5% 8% 9% 53%	2800
July	1st to 10th	Day	3 3 1 4 4 5% 5% 5% 8% 9% 52%	6339
	11th to 20th	Day	2 2 1 5% 5% 6% 7% 5% 8% 8% 50%	6340
	21st to end	Day	4 4 2 6% 5% 5% 6% 4 7% 9% 48%	6865
August	1st to 10th	Day	3 3 2 6% 5% 6% 6% 5% 8% 9% 47%	5779
	11th to 20th	Day	3 3 2 5% 4 5% 5% 4 6% 9% 53%	5523
	21st to end	Day	6% 4 2 7% 4 5% 6% 5% 7% 7% 47%	5984
September	1st to 10th	Day	4 4 1 5% 3 4 5% 4 5% 7% 58%	2400
	11th to 20th	Day	4 4 1 5% 4 3 4 4 6% 6% 59%	2400
	21st to end	Day	6% 5% 1 5% 3 3 3 2 4 6% 63%	2170
October	1st to 10th	Day	4 4 1 3 2 2 3 2 3 4 71%	3270
	11th to 20th	Day	3 5% 2 7% 4 4 4 3 5% 6% 58%	3230
	21st to end	Day	4 9% 3 5% 3 2 3 3 4 6% 59%	3298
November	1st to 10th	Day	3 6% 2 5% 2 3 3 3 5% 8% 59%	1763
	11th to 20th	Day	2 8% 2 5% 3 3 4 3 5% 7% 58%	1785
	21st to end	Day	2 6% 3 7% 4 3 4 3 6% 7% 55%	1600
December	1st to 10th	Day	1 4 2 9% 4 3 3 2 4 6% 63%	2620
	11th to 20th	Day	1 7% 3 5% 3 2 3 3 5% 8% 60%	3026
	21st to end	Day	2 9% 4 9% 5% 4 4 3 6% 7% 47%	4004
January	1st to 10th	Night	1 9% 5% 11% 5% 4 4 3 5% 6% 47%	6327
	11th to 20th	Night	5% 4 13% 6% 4 4 4 5% 8% 46%	6340
	21st to end	Night	1 5% 3 9% 5% 4 4 3 4 6% 56%	6472
February	1st to 10th	Night	1 7% 4 9% 4 3 4 3 5% 7% 51%	2600
	11th to 20th	Night	1 8% 3 8% 5% 6% 4 3 5% 7% 49%	2428
	21st to end	Night	1 7% 4 8% 4 3 3 3 4 7% 58%	1980
March	1st to 10th	Night	1 10% 4 7% 4 4 4 3 5% 6% 52%	5374
	11th to 20th	Night	1 7% 4 6% 3 4 4 4 5% 7% 55%	5000
	21st to end	Night	4 12% 3 8% 4 4 4 3 6% 8% 44%	5178
April	1st to 10th	Night	4 8% 3 6% 4 4 4 4 6% 7% 51%	2000
	11th to 20th	Night	6% 11% 3 6% 3 4 4 5% 5% 7% 46%	1977
	21st to end	Night	7% 11% 3 6% 3 3 3 4 5% 7% 48%	2000
May	1st to 10th	Night	5% 10% 3 6% 4 4 4 3 5% 7% 50%	3950
	11th to 20th	Night	6% 6% 2 6% 4 4 4 4 6% 9% 48%	3617
	21st to end	Night	6% 6% 2 5% 4 5% 4 4 6% 8% 51%	3972
June	1st to 10th	Night	4 3 1 3 3 4 4 4 7% 10% 57%	1600
	11th to 20th	Night	4 2 1 4 4 2 4 4 6% 8% 62%	1600
	21st to end	Night	3 3 2 4 3 3 4 3 6% 7% 62%	1600
July	1st to 10th	Night	3 3 2 5% 4 4 5% 4 6% 9% 55%	3640
	11th to 20th	Night	2 2 1 4 4 4 6% 5% 8% 10% 55%	3640
	21st to end	Night	2 2 1 5% 4 4 5% 5% 8% 9% 54%	4005
August	1st to 10th	Night	4 3 1 4 3 4 4 4 7% 10% 56%	4033
	11th to 20th	Night	2 3 2 5% 4 4 5% 5% 6% 9% 55%	4314
	21st to end	Night	4 4 2 5% 4 3 5% 5% 7% 9% 52%	4993
September	1st to 10th	Night	5% 4 2 3 3 3 4 3 5% 7% 62%	2000
	11th to 20th	Night	4 4 2 4 3 3 4 3 5% 7% 63%	2000
	21st to end	Night	5% 4 1 3 3 3 4 2 5% 6% 64%	2225
October	1st to 10th	Night	3 3 1 3 2 2 2 2 3 4 74%	3920
	11th to 20th	Night	4 4 2 5% 3 3 3 3 5% 8% 60%	3874
	21st to end	Night	4 6% 2 4 2 2 3 2 4 8% 63%	4227
November	1st to 10th	Night	3 6% 2 4 3 3 3 3 5% 8% 60%	2535
	11th to 20th	Night	3 7% 2 5% 3 3 3 3 5% 7% 59%	2610
	21st to end	Night	2 7% 3 6% 4 3 3 3 6% 8% 56%	2800
December	1st to 10th	Night	1 4 2 7% 3 3 2 2 4 6% 67%	4570
	11th to 20th	Night	1 5% 4 5% 3 2 4 3 6% 9% 58%	5181
	21st to end	Night	2 11% 4 9% 5% 4 4 3 5% 7% 45%	6974

Transparency (when cloud cover <= 30%)
Color Meanings: Too cloudy to forecast Poor Below Average Average Above average Transparent
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	34% 8% 15% 21% 20% 2	3639
	11th to 20th	Day	36% 13% 14% 17% 16% 4	3667
	21st to end	Day	25% 7% 16% 24% 23% 4	4510
February	1st to 10th	Day	35% 7% 18% 21% 16% 3	1800
	11th to 20th	Day	33% 8% 13% 27% 15% 3	1867
	21st to end	Day	27% 7% 16% 26% 20% 4	1650
March	1st to 10th	Day	30% 7% 8% 27% 21% 7%	4500
	11th to 20th	Day	31% 9% 11% 29% 18% 2	4996
	21st to end	Day	36% 8% 15% 32% 8% 1	5782
April	1st to 10th	Day	34% 8% 16% 23% 16% 4	2400
	11th to 20th	Day	42% 9% 11% 20% 15% 3	2374
	21st to end	Day	41% 9% 9% 25% 15% 1	2400
May	1st to 10th	Day	41% 6% 11% 22% 16% 4	6014
	11th to 20th	Day	35% 10% 9% 23% 20% 2	6302
	21st to end	Day	31% 8% 10% 25% 22% 4	6926
June	1st to 10th	Day	29% 9% 16% 22% 18% 6%	2800
	11th to 20th	Day	28% 9% 10% 17% 25% 12%	2800
	21st to end	Day	23% 9% 9% 22% 23% 14%	2800
July	1st to 10th	Day	24% 7% 5% 15% 27% 21%	6271
	11th to 20th	Day	27% 5% 7% 23% 23% 15%	6265
	21st to end	Day	31% 6% 8% 18% 20% 17%	6667
August	1st to 10th	Day	31% 6% 11% 24% 16% 12%	4208
	11th to 20th	Day	31% 5% 10% 16% 25% 13%	3993
	21st to end	Day	26% 4 10% 18% 26% 16%	4311
September	1st to 10th	Day	24% 5% 8% 19% 29% 15%	2400
	11th to 20th	Day	23% 6% 9% 23% 27% 12%	2400
	21st to end	Day	23% 5% 7% 23% 35% 7%	2170
October	1st to 10th	Day	18% 4 5% 19% 30% 24%	3270
	11th to 20th	Day	28% 4 8% 35% 20% 6%	3230
	21st to end	Day	28% 3 7% 34% 24% 3	3298
November	1st to 10th	Day	23% 6% 14% 28% 26% 3	1763
	11th to 20th	Day	23% 5% 16% 30% 23% 3	1785
	21st to end	Day	27% 7% 13% 31% 20% 4	1600
December	1st to 10th	Day	23% 5% 15% 36% 20% 3	2620
	11th to 20th	Day	23% 7% 18% 37% 15% 1	3024
	21st to end	Day	35% 6% 13% 25% 16% 4	4004
January	1st to 10th	Night	36% 6% 13% 25% 15% 4	6327
	11th to 20th	Night	32% 9% 15% 19% 20% 4	6340
	21st to end	Night	28% 7% 16% 25% 19% 4	6472
February	1st to 10th	Night	32% 6% 18% 27% 14% 2	2600
	11th to 20th	Night	33% 5% 14% 29% 15% 3	2429
	21st to end	Night	27% 4 15% 25% 23% 5%	1980
March	1st to 10th	Night	30% 7% 8% 28% 21% 7%	5374
	11th to 20th	Night	27% 6% 10% 28% 27% 2	5000
	21st to end	Night	36% 7% 16% 33% 9% 1	5178
April	1st to 10th	Night	29% 8% 15% 27% 16% 5%	2000
	11th to 20th	Night	35% 7% 12% 26% 17% 3	1977
	21st to end	Night	35% 6% 10% 29% 18%	2000
May	1st to 10th	Night	33% 6% 11% 31% 17% 3	3947
	11th to 20th	Night	30% 8% 13% 30% 15% 4	3618
	21st to end	Night	29% 6% 14% 28% 21% 1	3972
June	1st to 10th	Night	20% 9% 21% 28% 17% 5%	1600
	11th to 20th	Night	20% 6% 12% 25% 24% 13%	1600
	21st to end	Night	20% 6% 9% 25% 25% 16%	1600
July	1st to 10th	Night	25% 6% 7% 21% 26% 15%	3600
	11th to 20th	Night	22% 5% 13% 33% 17% 10%	3592
	21st to end	Night	24% 5% 13% 23% 21% 13%	3891
August	1st to 10th	Night	24% 5% 17% 26% 20% 8%	2928
	11th to 20th	Night	28% 4 16% 22% 19% 12%	3119
	21st to end	Night	22% 5% 14% 20% 29% 11%	3597
September	1st to 10th	Night	22% 5% 9% 22% 26% 15%	2000
	11th to 20th	Night	21% 5% 9% 26% 27% 12%	2000
	21st to end	Night	20% 5% 9% 25% 33% 8%	2225
October	1st to 10th	Night	15% 4 6% 19% 36% 20%	3920
	11th to 20th	Night	24% 4 11% 32% 25% 5%	3874
	21st to end	Night	22% 4 10% 36% 23% 5%	4227
November	1st to 10th	Night	23% 6% 14% 28% 25% 5%	2535
	11th to 20th	Night	24% 6% 14% 31% 20% 5%	2610
	21st to end	Night	26% 5% 12% 33% 20% 4	2800
December	1st to 10th	Night	20% 5% 15% 40% 18% 2	4570
	11th to 20th	Night	24% 6% 15% 40% 14% 2	5182
	21st to end	Night	37% 6% 12% 27% 16% 3	6974

Seeing (when cloud cover <= 80%)
Color Meanings: Too cloudy to forecast Bad 1/5 Poor 2/5 Average 3/5 Good 4/5 Excellent 5/5
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	11% 32% 32% 16% 7% 2	300
	11th to 20th	Day	9% 40% 33% 16% 2	300
	21st to end	Day	5% 38% 39% 15% 3	330
February	1st to 10th	Day	14% 45% 34% 5% 1	300
	11th to 20th	Day	10% 42% 35% 11% 1	300
	21st to end	Day	19% 35% 35% 11% 1	249
March	1st to 10th	Day	11% 36% 34% 15% 4	300
	11th to 20th	Day	13% 29% 38% 17% 2 1	496
	21st to end	Day	16% 29% 37% 15% 3	550
April	1st to 10th	Day	16% 33% 37% 12% 2	500
	11th to 20th	Day	20% 35% 30% 12% 3	492
	21st to end	Day	18% 25% 34% 17% 5% 1	500
May	1st to 10th	Day	19% 22% 30% 18% 9% 2	648
	11th to 20th	Day	16% 16% 31% 24% 11% 2	725
	21st to end	Day	11% 19% 28% 26% 14% 3	789
June	1st to 10th	Day	6% 15% 29% 30% 17% 4	730
	11th to 20th	Day	8% 14% 37% 27% 12% 2	730
	21st to end	Day	5% 14% 33% 28% 18% 2	730
July	1st to 10th	Day	7% 6% 22% 37% 25% 4	721
	11th to 20th	Day	4 5% 28% 38% 21% 4	718
	21st to end	Day	4 5% 25% 35% 26% 4	781
August	1st to 10th	Day	8% 6% 37% 34% 13% 2	527
	11th to 20th	Day	5% 6% 31% 36% 16% 5%	517
	21st to end	Day	7% 9% 33% 31% 16% 4	583
September	1st to 10th	Day	7% 10% 32% 29% 17% 4	530
	11th to 20th	Day	6% 15% 38% 25% 13% 3	530
	21st to end	Day	8% 15% 30% 22% 17% 7%	335
October	1st to 10th	Day	9% 18% 30% 25% 13% 5%	330
	11th to 20th	Day	12% 30% 29% 20% 4 4	324
	21st to end	Day	9% 31% 39% 15% 4 1	330
November	1st to 10th	Day	9% 31% 38% 16% 4 2	300
	11th to 20th	Day	12% 33% 42% 10% 3	300
	21st to end	Day	11% 34% 39% 14% 2	300
December	1st to 10th	Day	12% 37% 36% 9% 5%	300
	11th to 20th	Day	13% 44% 34% 9%	300
	21st to end	Day	16% 42% 28% 11% 2 1	330
January	1st to 10th	Night	7% 36% 37% 15% 6% 1	1000
	11th to 20th	Night	6% 43% 35% 12% 5%	1000
	21st to end	Night	4 32% 42% 17% 4	884
February	1st to 10th	Night	5% 38% 43% 9% 4	800
	11th to 20th	Night	6% 33% 41% 17% 2	784
	21st to end	Night	8% 36% 44% 11% 1	660
March	1st to 10th	Night	5% 29% 43% 18% 4 1	800
	11th to 20th	Night	8% 20% 41% 26% 5%	800
	21st to end	Night	10% 20% 44% 21% 5% 1	750
April	1st to 10th	Night	10% 22% 42% 24% 3	600
	11th to 20th	Night	13% 22% 39% 21% 4	593
	21st to end	Night	15% 17% 34% 26% 8% 1	600
May	1st to 10th	Night	13% 15% 34% 29% 9% 1	600
	11th to 20th	Night	13% 9% 33% 34% 12% 1	591
	21st to end	Night	7% 10% 36% 30% 15% 1	650
June	1st to 10th	Night	5% 10% 31% 39% 15% 1	600
	11th to 20th	Night	7% 9% 38% 38% 9%	600
	21st to end	Night	4 7% 30% 41% 17%	600
July	1st to 10th	Night	5% 3 26% 45% 21% 1	585
	11th to 20th	Night	3 1 23% 51% 20% 2	582
	21st to end	Night	4 2 21% 47% 24% 1	657
August	1st to 10th	Night	5% 2 25% 49% 18% 1	597
	11th to 20th	Night	3 1 25% 50% 19% 2	594
	21st to end	Night	5% 2 25% 43% 24% 1	660
September	1st to 10th	Night	7% 4 23% 46% 18% 2	600
	11th to 20th	Night	5% 5% 28% 45% 16% 2	600
	21st to end	Night	6% 8% 33% 37% 16% 1	630
October	1st to 10th	Night	7% 14% 34% 32% 12% 1	800
	11th to 20th	Night	8% 18% 37% 29% 8% 1	792
	21st to end	Night	10% 19% 44% 21% 5% 1	894
November	1st to 10th	Night	6% 24% 44% 20% 5% 1	975
	11th to 20th	Night	9% 33% 43% 14% 2	1000
	21st to end	Night	7% 27% 47% 16% 3	1000
December	1st to 10th	Night	7% 38% 37% 15% 3	1000
	11th to 20th	Night	6% 38% 41% 14% 2	1000
	21st to end	Night	8% 43% 34% 12% 4	1100

Page generated at 2025-10-15 23:50:24. Version ac07

Copyright © 2025 Attilla Danko.