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 2024-04-10.

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	4 6% 3 6% 5% 3 5% 5% 6% 8% 49%	83204
	Night	3 6% 3 5% 4 3 4 4 5% 8% 54%	85674
Transparency	Day	31% 9% 13% 24% 18% 6%	82908
	Night	27% 8% 15% 28% 18% 5%	85492
Seeing	Day	10% 22% 32% 22% 11% 2	14820
	Night	7% 22% 36% 25% 9% 1	25028

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	1 4 4 7% 9% 3 4 4 4 6% 53%	2538
	11th to 20th	Day	9% 5% 9% 9% 4 5% 6% 5% 7% 41%	2553
	21st to end	Day	1 4 3 6% 4 3 5% 5% 5% 7% 58%	3146
February	1st to 10th	Day	2 8% 3 9% 8% 4 4 5% 5% 8% 45%	1710
	11th to 20th	Day	1 8% 3 8% 5% 4 5% 4 6% 9% 46%	1762
	21st to end	Day	1 7% 4 7% 5% 3 4 5% 6% 8% 52%	1570
March	1st to 10th	Day	2 8% 4 8% 5% 2 4 5% 5% 8% 50%	3130
	11th to 20th	Day	3 10% 4 6% 5% 3 4 5% 6% 8% 46%	3486
	21st to end	Day	3 9% 4 8% 8% 4 5% 5% 6% 7% 40%	4030
April	1st to 10th	Day	4 10% 3 6% 5% 3 4 5% 7% 7% 46%	2269
	11th to 20th	Day	7% 11% 4 7% 6% 3 5% 5% 5% 8% 37%	2131
	21st to end	Day	8% 11% 4 6% 6% 3 5% 5% 7% 7% 39%	2160
May	1st to 10th	Day	9% 11% 3 8% 6% 3 5% 5% 6% 7% 37%	2381
	11th to 20th	Day	11% 9% 3 5% 5% 4 6% 5% 6% 8% 37%	2478
	21st to end	Day	8% 6% 3 6% 7% 4 7% 7% 8% 9% 37%	2724
June	1st to 10th	Day	5% 4 2 5% 5% 3 6% 6% 8% 10% 46%	2520
	11th to 20th	Day	6% 4 2 4 4 3 5% 6% 7% 8% 51%	2520
	21st to end	Day	3 3 2 4 5% 3 5% 6% 8% 9% 53%	2520
July	1st to 10th	Day	5% 4 2 5% 6% 4 6% 6% 8% 8% 46%	2520
	11th to 20th	Day	3 3 2 4 5% 3 5% 6% 7% 11% 50%	2520
	21st to end	Day	5% 4 2 6% 6% 4 6% 7% 7% 10% 44%	2731
August	1st to 10th	Day	5% 5% 3 6% 6% 4 6% 7% 8% 9% 42%	2328
	11th to 20th	Day	6% 4 3 5% 5% 4 5% 5% 7% 8% 49%	2192
	21st to end	Day	5% 3 2 5% 5% 3 6% 6% 7% 8% 51%	2376
September	1st to 10th	Day	5% 4 2 4 3 3 5% 4 4 8% 58%	2160
	11th to 20th	Day	4 4 1 4 4 2 4 5% 5% 6% 60%	2160
	21st to end	Day	6% 5% 1 4 4 2 3 3 4 6% 63%	1954
October	1st to 10th	Day	6% 6% 2 4 4 3 4 5% 4 7% 55%	1800
	11th to 20th	Day	4 6% 2 4 3 2 4 3 5% 6% 60%	1800
	21st to end	Day	4 8% 4 5% 3 2 3 3 4 7% 58%	1906
November	1st to 10th	Day	3 5% 2 3 3 2 4 4 4 9% 61%	1673
	11th to 20th	Day	3 7% 3 5% 3 2 3 4 5% 8% 58%	1696
	21st to end	Day	2 5% 3 6% 4 2 4 4 6% 7% 55%	1520
December	1st to 10th	Day	1 6% 4 7% 6% 3 4 4 6% 8% 50%	1520
	11th to 20th	Day	2 6% 3 4 4 2 4 4 6% 11% 54%	1926
	21st to end	Day	2 9% 4 8% 6% 3 4 3 5% 7% 49%	2794
January	1st to 10th	Night	6% 5% 9% 6% 3 4 4 5% 7% 51%	4417
	11th to 20th	Night	1 6% 5% 10% 5% 3 4 5% 5% 9% 48%	4430
	21st to end	Night	1 6% 3 5% 5% 3 5% 5% 5% 7% 56%	4525
February	1st to 10th	Night	1 7% 4 8% 5% 2 5% 4 5% 8% 51%	2470
	11th to 20th	Night	2 7% 4 7% 6% 4 5% 4 5% 8% 50%	2304
	21st to end	Night	1 6% 4 7% 5% 2 3 3 4 7% 57%	1884
March	1st to 10th	Night	1 6% 3 7% 5% 3 4 5% 5% 7% 53%	3734
	11th to 20th	Night	2 8% 4 6% 4 3 3 5% 5% 7% 53%	3490
	21st to end	Night	4 9% 3 7% 6% 3 4 4 6% 7% 46%	3615
April	1st to 10th	Night	4 7% 3 5% 4 3 4 5% 6% 7% 51%	1900
	11th to 20th	Night	6% 10% 3 6% 4 3 4 5% 5% 7% 46%	1777
	21st to end	Night	7% 11% 3 6% 4 2 4 4 5% 7% 48%	1800
May	1st to 10th	Night	8% 9% 3 5% 4 3 5% 4 6% 8% 44%	1576
	11th to 20th	Night	9% 6% 2 5% 5% 4 4 5% 5% 10% 45%	1417
	21st to end	Night	4 5% 2 4 4 4 5% 7% 7% 9% 49%	1552
June	1st to 10th	Night	4 3 1 2 4 3 4 5% 7% 11% 57%	1440
	11th to 20th	Night	4 2 1 3 4 2 4 4 5% 8% 62%	1440
	21st to end	Night	3 3 1 3 3 3 3 4 6% 8% 63%	1440
July	1st to 10th	Night	3 3 1 3 4 3 5% 5% 7% 10% 55%	1440
	11th to 20th	Night	2 2 2 3 4 2 4 5% 6% 10% 61%	1440
	21st to end	Night	2 3 1 3 3 3 5% 6% 8% 11% 54%	1584
August	1st to 10th	Night	3 3 2 4 5% 4 5% 5% 7% 10% 53%	1611
	11th to 20th	Night	3 2 2 4 4 3 3 4 5% 8% 63%	1709
	21st to end	Night	3 3 1 3 4 3 4 5% 6% 8% 59%	1980
September	1st to 10th	Night	6% 4 1 3 4 2 4 4 5% 7% 61%	1800
	11th to 20th	Night	4 3 2 3 4 2 3 3 5% 7% 65%	1800
	21st to end	Night	5% 3 1 3 3 2 4 3 4 7% 64%	2001
October	1st to 10th	Night	5% 5% 2 4 4 2 4 5% 5% 7% 57%	2160
	11th to 20th	Night	4 4 2 4 3 1 3 3 4 7% 65%	2160
	21st to end	Night	5% 7% 2 5% 3 2 3 3 4 8% 57%	2430
November	1st to 10th	Night	3 6% 2 3 3 2 3 4 5% 8% 62%	2405
	11th to 20th	Night	3 7% 3 4 4 2 3 4 6% 6% 59%	2479
	21st to end	Night	2 7% 3 5% 4 2 2 5% 6% 8% 56%	2660
December	1st to 10th	Night	1 5% 3 7% 4 3 4 4 5% 8% 57%	2660
	11th to 20th	Night	2 5% 3 5% 4 2 3 4 6% 10% 55%	3271
	21st to end	Night	2 10% 4 6% 6% 3 4 4 5% 8% 48%	4873

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	28% 11% 16% 21% 21% 2	2539
	11th to 20th	Day	33% 16% 20% 18% 12% 2	2553
	21st to end	Day	22% 8% 22% 30% 15% 3	3146
February	1st to 10th	Day	36% 7% 18% 21% 15% 2	1710
	11th to 20th	Day	32% 8% 14% 28% 15% 4	1771
	21st to end	Day	28% 7% 17% 26% 19% 3	1570
March	1st to 10th	Day	27% 8% 12% 32% 17% 3	3130
	11th to 20th	Day	30% 12% 16% 31% 10% 2	3486
	21st to end	Day	37% 10% 15% 30% 6% 2	4030
April	1st to 10th	Day	33% 8% 16% 22% 16% 5%	2269
	11th to 20th	Day	42% 9% 12% 21% 14% 2	2134
	21st to end	Day	41% 10% 9% 26% 14% 1	2160
May	1st to 10th	Day	45% 9% 11% 21% 14% 1	2381
	11th to 20th	Day	43% 10% 12% 24% 10% 1	2482
	21st to end	Day	39% 11% 13% 22% 13% 3	2724
June	1st to 10th	Day	30% 9% 16% 21% 17% 6%	2520
	11th to 20th	Day	27% 9% 10% 17% 24% 13%	2520
	21st to end	Day	23% 10% 9% 22% 22% 14%	2520
July	1st to 10th	Day	31% 10% 10% 17% 22% 10%	2451
	11th to 20th	Day	25% 9% 12% 18% 23% 15%	2445
	21st to end	Day	32% 9% 11% 22% 18% 9%	2579
August	1st to 10th	Day	33% 10% 13% 20% 15% 9%	2313
	11th to 20th	Day	30% 8% 11% 17% 23% 12%	2192
	21st to end	Day	29% 7% 10% 17% 27% 10%	2376
September	1st to 10th	Day	24% 5% 8% 17% 29% 16%	2160
	11th to 20th	Day	22% 7% 9% 23% 27% 13%	2160
	21st to end	Day	24% 5% 7% 24% 35% 6%	1954
October	1st to 10th	Day	28% 7% 9% 26% 22% 7%	1800
	11th to 20th	Day	24% 6% 9% 31% 23% 7%	1800
	21st to end	Day	27% 5% 11% 30% 21% 5%	1906
November	1st to 10th	Day	21% 7% 14% 28% 27% 3	1673
	11th to 20th	Day	24% 6% 16% 30% 21% 3	1696
	21st to end	Day	26% 7% 13% 31% 20% 3	1520
December	1st to 10th	Day	31% 7% 22% 23% 15% 2	1520
	11th to 20th	Day	24% 10% 16% 35% 14% 1	1924
	21st to end	Day	34% 7% 13% 24% 16% 6%	2794
January	1st to 10th	Night	30% 8% 15% 31% 14% 3	4417
	11th to 20th	Night	27% 12% 20% 20% 15% 5%	4430
	21st to end	Night	26% 9% 22% 28% 12% 4	4525
February	1st to 10th	Night	32% 6% 19% 27% 14% 2	2470
	11th to 20th	Night	33% 6% 14% 29% 16% 3	2305
	21st to end	Night	28% 5% 15% 25% 22% 5%	1884
March	1st to 10th	Night	25% 9% 11% 33% 19% 3	3734
	11th to 20th	Night	29% 8% 14% 33% 14% 2	3490
	21st to end	Night	33% 9% 15% 34% 8% 1	3615
April	1st to 10th	Night	29% 8% 15% 26% 16% 5%	1900
	11th to 20th	Night	35% 7% 12% 27% 15% 3	1777
	21st to end	Night	36% 6% 10% 29% 18% 1	1800
May	1st to 10th	Night	37% 9% 12% 26% 14% 1	1576
	11th to 20th	Night	36% 8% 17% 28% 12%	1418
	21st to end	Night	29% 9% 17% 26% 16% 2	1552
June	1st to 10th	Night	19% 10% 22% 28% 16% 5%	1440
	11th to 20th	Night	20% 6% 13% 23% 24% 13%	1440
	21st to end	Night	19% 6% 9% 25% 25% 15%	1440
July	1st to 10th	Night	21% 10% 13% 25% 22% 10%	1400
	11th to 20th	Night	18% 8% 13% 24% 22% 16%	1392
	21st to end	Night	20% 10% 16% 29% 17% 8%	1496
August	1st to 10th	Night	24% 8% 16% 27% 16% 8%	1602
	11th to 20th	Night	20% 5% 12% 26% 24% 13%	1709
	21st to end	Night	21% 7% 11% 24% 28% 10%	1980
September	1st to 10th	Night	23% 6% 9% 20% 26% 17%	1800
	11th to 20th	Night	20% 6% 9% 26% 26% 13%	1800
	21st to end	Night	20% 6% 9% 26% 33% 7%	2001
October	1st to 10th	Night	25% 7% 11% 26% 24% 7%	2160
	11th to 20th	Night	21% 6% 11% 32% 23% 8%	2160
	21st to end	Night	26% 6% 14% 28% 21% 5%	2430
November	1st to 10th	Night	21% 6% 15% 28% 25% 5%	2405
	11th to 20th	Night	24% 6% 15% 32% 19% 5%	2479
	21st to end	Night	26% 6% 13% 32% 20% 4	2660
December	1st to 10th	Night	25% 8% 21% 27% 17% 3	2660
	11th to 20th	Night	24% 8% 17% 35% 15% 1	3272
	21st to end	Night	32% 8% 13% 25% 17% 4	4873

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% 33% 31% 16% 7% 2	270
	11th to 20th	Day	10% 42% 30% 16% 3	270
	21st to end	Day	5% 38% 40% 13% 3	297
February	1st to 10th	Day	13% 46% 34% 6% 1	270
	11th to 20th	Day	11% 43% 36% 9% 1	270
	21st to end	Day	19% 37% 34% 9%	225
March	1st to 10th	Day	11% 38% 35% 13% 3	270
	11th to 20th	Day	12% 30% 37% 18% 2 1	456
	21st to end	Day	16% 31% 37% 13% 3	506
April	1st to 10th	Day	17% 33% 37% 11% 2	457
	11th to 20th	Day	20% 37% 30% 11% 3	412
	21st to end	Day	18% 26% 34% 16% 5% 1	420
May	1st to 10th	Day	18% 23% 31% 19% 9% 2	553
	11th to 20th	Day	17% 16% 30% 24% 12% 2	625
	21st to end	Day	11% 19% 27% 26% 14% 3	679
June	1st to 10th	Day	5% 15% 28% 30% 18% 4	630
	11th to 20th	Day	8% 14% 38% 27% 11% 1	630
	21st to end	Day	4 13% 34% 29% 19% 1	630
July	1st to 10th	Day	8% 5% 21% 37% 26% 4	621
	11th to 20th	Day	4 6% 29% 36% 21% 3	618
	21st to end	Day	4 5% 25% 35% 26% 4	673
August	1st to 10th	Day	9% 5% 38% 33% 13% 2	447
	11th to 20th	Day	6% 7% 31% 36% 15% 5%	437
	21st to end	Day	6% 10% 32% 32% 17% 4	495
September	1st to 10th	Day	7% 11% 34% 28% 16% 3	450
	11th to 20th	Day	5% 15% 38% 26% 14% 3	450
	21st to end	Day	9% 16% 31% 21% 16% 6%	275
October	1st to 10th	Day	10% 20% 29% 23% 13% 5%	270
	11th to 20th	Day	11% 31% 31% 20% 4 3	270
	21st to end	Day	9% 33% 38% 15% 4 1	297
November	1st to 10th	Day	8% 34% 38% 14% 4 2	270
	11th to 20th	Day	13% 32% 43% 10% 3	270
	21st to end	Day	11% 35% 39% 13% 2	270
December	1st to 10th	Day	13% 40% 36% 7% 5%	270
	11th to 20th	Day	12% 44% 34% 9%	270
	21st to end	Day	14% 44% 28% 10% 2 1	297
January	1st to 10th	Night	6% 37% 36% 14% 6% 1	950
	11th to 20th	Night	6% 43% 34% 11% 5%	950
	21st to end	Night	5% 32% 43% 16% 4	840
February	1st to 10th	Night	5% 38% 42% 10% 4	760
	11th to 20th	Night	6% 35% 39% 17% 3	744
	21st to end	Night	8% 37% 43% 11% 1	628
March	1st to 10th	Night	5% 30% 43% 18% 4 1	760
	11th to 20th	Night	8% 21% 41% 25% 5%	760
	21st to end	Night	10% 20% 44% 21% 5% 1	713
April	1st to 10th	Night	10% 22% 42% 22% 3	570
	11th to 20th	Night	13% 22% 39% 20% 5%	533
	21st to end	Night	15% 18% 32% 27% 8% 1	540
May	1st to 10th	Night	13% 14% 33% 29% 10% 1	540
	11th to 20th	Night	14% 8% 31% 34% 12% 1	531
	21st to end	Night	6% 11% 35% 31% 16% 1	584
June	1st to 10th	Night	5% 8% 30% 40% 16% 1	540
	11th to 20th	Night	6% 8% 39% 37% 9%	540
	21st to end	Night	4 7% 29% 42% 18%	540
July	1st to 10th	Night	4 2 24% 46% 23% 1	525
	11th to 20th	Night	3 1 23% 51% 20% 2	522
	21st to end	Night	4 2 21% 46% 26% 2	591
August	1st to 10th	Night	4 2 23% 50% 20% 1	537
	11th to 20th	Night	3 1 23% 51% 19% 2	534
	21st to end	Night	5% 3 23% 43% 26% 1	594
September	1st to 10th	Night	8% 4 23% 44% 18% 2	540
	11th to 20th	Night	5% 5% 27% 44% 17% 2	540
	21st to end	Night	6% 9% 34% 35% 16% 1	566
October	1st to 10th	Night	7% 16% 34% 29% 12% 1	720
	11th to 20th	Night	8% 19% 37% 28% 8% 1	720
	21st to end	Night	10% 20% 43% 20% 5% 1	846
November	1st to 10th	Night	6% 25% 44% 19% 5% 1	925
	11th to 20th	Night	9% 34% 42% 14% 2	950
	21st to end	Night	7% 28% 45% 17% 3	950
December	1st to 10th	Night	7% 39% 37% 13% 3	950
	11th to 20th	Night	6% 38% 40% 14% 2	950
	21st to end	Night	7% 44% 33% 12% 4	1045

Page generated at 2024-04-07 07:28:12. Version ac07

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