Leadville
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Leadville clear sky chart from 2005-11-06 to 2024-03-06.

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% 4 8% 8% 4 5% 5% 5% 7% 44%	78642
	Night	1 4 3 7% 7% 4 5% 5% 6% 8% 51%	80939
Transparency	Day	35% 9% 13% 20% 17% 6%	78355
	Night	25% 10% 16% 24% 19% 6%	80748
Seeing	Day	16% 25% 29% 19% 10% 2	14498
	Night	8% 20% 30% 27% 14% 2	24753

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	2 4 8% 11% 7% 7% 5% 6% 8% 41%	2538
	11th to 20th	Day	2 5% 13% 12% 7% 7% 4 4 4 41%	2798
	21st to end	Day	5% 5% 12% 9% 4 5% 5% 4 7% 44%	3146
February	1st to 10th	Day	3 4 14% 10% 6% 6% 4 6% 6% 41%	1710
	11th to 20th	Day	4 5% 10% 9% 5% 6% 4 5% 6% 44%	1766
	21st to end	Day	3 4 13% 9% 6% 6% 5% 4 6% 44%	1570
March	1st to 10th	Day	7% 4 11% 9% 5% 4 3 5% 8% 44%	1912
	11th to 20th	Day	1 7% 5% 9% 9% 4 5% 4 6% 7% 43%	1980
	21st to end	Day	1 7% 6% 11% 8% 4 6% 5% 6% 8% 37%	2254
April	1st to 10th	Day	2 7% 4 8% 7% 4 6% 5% 5% 8% 43%	2160
	11th to 20th	Day	1 10% 5% 11% 9% 5% 6% 5% 5% 5% 36%	2131
	21st to end	Day	2 10% 6% 9% 9% 5% 6% 6% 6% 7% 35%	2160
May	1st to 10th	Day	3 11% 5% 9% 7% 4 6% 6% 6% 8% 35%	2235
	11th to 20th	Day	4 12% 4 8% 7% 4 6% 5% 6% 7% 36%	2478
	21st to end	Day	5% 9% 4 7% 7% 4 6% 6% 6% 8% 37%	2724
June	1st to 10th	Day	4 5% 3 5% 5% 4 5% 6% 7% 9% 47%	2520
	11th to 20th	Day	5% 5% 2 6% 5% 3 5% 5% 5% 7% 54%	2520
	21st to end	Day	4 4 2 5% 6% 4 5% 6% 6% 7% 50%	2520
July	1st to 10th	Day	9% 6% 2 6% 7% 5% 5% 5% 5% 8% 42%	2520
	11th to 20th	Day	7% 6% 3 7% 7% 4 7% 6% 8% 8% 37%	2520
	21st to end	Day	11% 8% 4 9% 9% 5% 6% 6% 6% 8% 28%	2569
August	1st to 10th	Day	13% 6% 4 8% 8% 5% 5% 5% 6% 9% 30%	2328
	11th to 20th	Day	9% 5% 4 7% 7% 4 5% 6% 6% 7% 41%	2179
	21st to end	Day	8% 7% 4 9% 8% 4 5% 6% 6% 7% 37%	2376
September	1st to 10th	Day	8% 6% 3 5% 6% 4 4 4 5% 6% 49%	2160
	11th to 20th	Day	7% 7% 2 6% 6% 3 5% 4 4 7% 49%	2160
	21st to end	Day	5% 7% 2 5% 5% 2 3 4 4 5% 56%	1938
October	1st to 10th	Day	6% 7% 4 5% 6% 3 4 4 5% 6% 50%	1800
	11th to 20th	Day	2 5% 2 5% 4 2 4 4 4 7% 62%	1800
	21st to end	Day	2 5% 3 8% 6% 3 4 3 4 6% 57%	1980
November	1st to 10th	Day	1 4 3 4 5% 2 4 4 4 6% 63%	1691
	11th to 20th	Day	4 3 6% 4 3 3 3 4 8% 62%	1710
	21st to end	Day	4 4 6% 7% 3 4 3 4 7% 57%	1549
December	1st to 10th	Day	3 4 10% 9% 5% 5% 4 5% 8% 48%	1520
	11th to 20th	Day	3 5% 9% 7% 4 4 5% 6% 11% 46%	1926
	21st to end	Day	3 3 10% 10% 4 6% 4 6% 9% 44%	2794
January	1st to 10th	Night	1 2 10% 14% 6% 5% 5% 6% 9% 41%	4417
	11th to 20th	Night	1 4 12% 13% 5% 8% 4 4 6% 42%	4202
	21st to end	Night	4 5% 11% 9% 5% 6% 6% 7% 9% 38%	4521
February	1st to 10th	Night	2 3 10% 9% 5% 6% 6% 6% 8% 46%	2470
	11th to 20th	Night	2 3 7% 9% 5% 7% 7% 6% 8% 46%	2300
	21st to end	Night	3 4 8% 8% 5% 6% 6% 5% 8% 46%	1884
March	1st to 10th	Night	4 3 7% 6% 4 4 5% 6% 9% 53%	2162
	11th to 20th	Night	4 3 6% 7% 4 4 4 5% 8% 53%	1980
	21st to end	Night	1 5% 4 7% 7% 5% 5% 5% 7% 8% 46%	2100
April	1st to 10th	Night	1 3 2 5% 6% 3 5% 6% 6% 10% 53%	1800
	11th to 20th	Night	1 7% 3 7% 6% 5% 5% 5% 6% 8% 47%	1777
	21st to end	Night	2 7% 3 5% 5% 4 5% 5% 6% 8% 50%	1800
May	1st to 10th	Night	2 8% 3 6% 6% 2 5% 5% 6% 8% 49%	1718
	11th to 20th	Night	3 10% 3 7% 5% 3 6% 5% 6% 8% 45%	1417
	21st to end	Night	3 6% 3 4 4 3 5% 5% 7% 9% 51%	1552
June	1st to 10th	Night	2 4 1 4 3 1 4 5% 5% 10% 62%	1440
	11th to 20th	Night	3 4 2 2 4 3 3 4 4 7% 63%	1440
	21st to end	Night	3 3 1 3 3 3 4 5% 6% 10% 60%	1440
July	1st to 10th	Night	5% 5% 3 6% 5% 3 5% 6% 8% 9% 46%	1440
	11th to 20th	Night	2 3 2 4 6% 4 5% 4 8% 10% 54%	1440
	21st to end	Night	5% 5% 3 6% 5% 4 5% 7% 8% 11% 41%	1745
August	1st to 10th	Night	6% 5% 3 6% 6% 3 5% 6% 6% 10% 45%	1611
	11th to 20th	Night	6% 5% 2 4 4 3 4 5% 7% 8% 52%	1722
	21st to end	Night	4 4 2 6% 6% 3 6% 6% 7% 7% 49%	1980
September	1st to 10th	Night	4 3 2 5% 5% 3 3 6% 6% 9% 54%	1800
	11th to 20th	Night	4 5% 2 4 4 3 4 4 5% 7% 60%	1800
	21st to end	Night	2 4 2 3 4 2 4 4 6% 6% 62%	2018
October	1st to 10th	Night	3 6% 1 4 4 3 4 5% 6% 7% 56%	2160
	11th to 20th	Night	1 3 2 4 3 2 3 3 5% 6% 68%	2160
	21st to end	Night	2 5% 2 7% 4 2 3 4 4 7% 59%	2376
November	1st to 10th	Night	3 3 4 3 2 3 3 5% 6% 66%	2367
	11th to 20th	Night	2 2 5% 5% 4 4 4 5% 8% 62%	2470
	21st to end	Night	3 3 6% 5% 3 6% 5% 6% 8% 56%	2626
December	1st to 10th	Night	3 2 7% 7% 4 6% 4 5% 8% 55%	2660
	11th to 20th	Night	3 3 7% 7% 5% 6% 6% 6% 10% 48%	3271
	21st to end	Night	3 3 8% 9% 5% 6% 6% 6% 9% 46%	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	27% 15% 18% 18% 18% 4	2539
	11th to 20th	Day	30% 21% 18% 18% 11% 3	2798
	21st to end	Day	33% 10% 13% 23% 15% 5%	3146
February	1st to 10th	Day	40% 8% 16% 16% 14% 5%	1710
	11th to 20th	Day	34% 9% 12% 21% 18% 6%	1775
	21st to end	Day	37% 8% 12% 19% 18% 6%	1570
March	1st to 10th	Day	36% 6% 12% 24% 20% 2	1912
	11th to 20th	Day	36% 8% 16% 23% 14% 3	1980
	21st to end	Day	42% 9% 13% 22% 12% 2	2254
April	1st to 10th	Day	36% 8% 14% 21% 14% 6%	2160
	11th to 20th	Day	45% 8% 14% 16% 15% 2	2134
	21st to end	Day	43% 8% 13% 23% 11% 2	2160
May	1st to 10th	Day	43% 9% 13% 20% 14% 1	2235
	11th to 20th	Day	45% 9% 15% 22% 8% 1	2482
	21st to end	Day	42% 8% 13% 20% 14% 4	2724
June	1st to 10th	Day	30% 10% 14% 22% 19% 6%	2520
	11th to 20th	Day	29% 7% 9% 19% 22% 14%	2520
	21st to end	Day	30% 7% 11% 18% 22% 11%	2520
July	1st to 10th	Day	40% 8% 9% 16% 18% 10%	2451
	11th to 20th	Day	40% 11% 14% 16% 12% 7%	2445
	21st to end	Day	50% 12% 15% 13% 8% 2	2426
August	1st to 10th	Day	49% 10% 12% 12% 12% 5%	2313
	11th to 20th	Day	39% 9% 13% 15% 17% 6%	2179
	21st to end	Day	43% 9% 10% 19% 14% 4	2376
September	1st to 10th	Day	35% 7% 9% 15% 23% 11%	2160
	11th to 20th	Day	32% 7% 11% 18% 23% 8%	2160
	21st to end	Day	30% 5% 9% 24% 27% 6%	1938
October	1st to 10th	Day	33% 7% 10% 18% 25% 7%	1800
	11th to 20th	Day	22% 6% 9% 26% 29% 9%	1800
	21st to end	Day	28% 6% 11% 28% 21% 7%	1980
November	1st to 10th	Day	21% 5% 14% 23% 31% 5%	1691
	11th to 20th	Day	19% 6% 16% 30% 22% 7%	1710
	21st to end	Day	27% 6% 12% 27% 18% 11%	1549
December	1st to 10th	Day	31% 10% 16% 24% 15% 4	1520
	11th to 20th	Day	28% 10% 14% 27% 19% 2	1924
	21st to end	Day	29% 13% 14% 15% 22% 8%	2794
January	1st to 10th	Night	28% 14% 15% 24% 15% 4	4417
	11th to 20th	Night	24% 21% 18% 21% 12% 4	4202
	21st to end	Night	29% 12% 14% 24% 16% 5%	4521
February	1st to 10th	Night	31% 8% 18% 22% 16% 5%	2470
	11th to 20th	Night	29% 9% 16% 22% 20% 5%	2301
	21st to end	Night	29% 9% 14% 22% 19% 7%	1884
March	1st to 10th	Night	25% 9% 14% 27% 22% 3	2162
	11th to 20th	Night	25% 8% 18% 30% 15% 5%	1980
	21st to end	Night	29% 10% 18% 27% 13% 2	2100
April	1st to 10th	Night	22% 10% 19% 24% 20% 5%	1800
	11th to 20th	Night	30% 9% 16% 28% 15% 2	1777
	21st to end	Night	28% 9% 18% 29% 16% 1	1800
May	1st to 10th	Night	31% 9% 15% 29% 14% 1	1718
	11th to 20th	Night	35% 10% 16% 26% 12%	1418
	21st to end	Night	26% 8% 15% 26% 20% 4	1552
June	1st to 10th	Night	17% 9% 16% 30% 21% 6%	1440
	11th to 20th	Night	19% 8% 12% 19% 28% 14%	1440
	21st to end	Night	17% 8% 12% 23% 26% 13%	1440
July	1st to 10th	Night	30% 11% 16% 16% 19% 8%	1400
	11th to 20th	Night	22% 10% 21% 22% 18% 7%	1392
	21st to end	Night	31% 15% 25% 19% 9% 2	1648
August	1st to 10th	Night	31% 12% 20% 19% 13% 5%	1602
	11th to 20th	Night	27% 8% 20% 18% 22% 6%	1722
	21st to end	Night	29% 10% 17% 23% 18% 4	1980
September	1st to 10th	Night	24% 9% 14% 18% 26% 9%	1800
	11th to 20th	Night	23% 6% 15% 23% 24% 9%	1800
	21st to end	Night	21% 6% 13% 31% 26% 4	2018
October	1st to 10th	Night	23% 8% 13% 24% 22% 9%	2160
	11th to 20th	Night	15% 6% 12% 29% 28% 9%	2160
	21st to end	Night	23% 6% 14% 28% 22% 7%	2376
November	1st to 10th	Night	17% 7% 13% 26% 29% 7%	2367
	11th to 20th	Night	17% 9% 15% 30% 23% 7%	2470
	21st to end	Night	24% 7% 12% 27% 21% 9%	2626
December	1st to 10th	Night	23% 11% 19% 23% 17% 6%	2660
	11th to 20th	Night	25% 10% 16% 22% 23% 4	3272
	21st to end	Night	27% 12% 13% 18% 19% 11%	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	21% 28% 23% 20% 7% 1	270
	11th to 20th	Day	23% 36% 21% 16% 3	270
	21st to end	Day	14% 35% 31% 15% 5% 1	297
February	1st to 10th	Day	28% 42% 20% 8% 1 1	270
	11th to 20th	Day	31% 34% 23% 9% 3	270
	21st to end	Day	33% 36% 24% 8%	225
March	1st to 10th	Day	26% 36% 24% 12% 3	317
	11th to 20th	Day	21% 31% 31% 13% 3	420
	21st to end	Day	20% 42% 29% 8% 1	462
April	1st to 10th	Day	18% 41% 29% 8% 3 1	420
	11th to 20th	Day	27% 36% 25% 10% 1	412
	21st to end	Day	17% 43% 28% 9% 2 1	420
May	1st to 10th	Day	19% 34% 29% 14% 3 1	436
	11th to 20th	Day	14% 21% 33% 21% 9% 2	625
	21st to end	Day	14% 21% 30% 24% 10% 2	679
June	1st to 10th	Day	9% 18% 29% 24% 18% 2	630
	11th to 20th	Day	10% 21% 34% 21% 12% 2	630
	21st to end	Day	7% 18% 32% 23% 18% 2	630
July	1st to 10th	Day	9% 8% 29% 29% 21% 4	621
	11th to 20th	Day	10% 7% 25% 29% 23% 6%	618
	21st to end	Day	15% 10% 26% 31% 16% 3	511
August	1st to 10th	Day	13% 12% 36% 23% 12% 3	447
	11th to 20th	Day	9% 11% 35% 27% 13% 5%	437
	21st to end	Day	11% 13% 29% 31% 12% 3	495
September	1st to 10th	Day	13% 16% 30% 23% 12% 5%	450
	11th to 20th	Day	11% 18% 39% 20% 9% 3	450
	21st to end	Day	12% 19% 30% 23% 11% 4	302
October	1st to 10th	Day	13% 20% 24% 21% 18% 3	270
	11th to 20th	Day	19% 27% 27% 16% 8% 2	270
	21st to end	Day	17% 29% 31% 15% 7% 1	297
November	1st to 10th	Day	22% 34% 24% 13% 7% 1	270
	11th to 20th	Day	20% 29% 31% 13% 4 1	270
	21st to end	Day	12% 32% 35% 17% 3	270
December	1st to 10th	Day	23% 34% 24% 11% 7% 1	270
	11th to 20th	Day	22% 36% 27% 10% 4 1	270
	21st to end	Day	24% 35% 25% 11% 4	297
January	1st to 10th	Night	13% 28% 28% 22% 9% 1	950
	11th to 20th	Night	14% 26% 32% 19% 8% 1	813
	21st to end	Night	7% 26% 38% 21% 7% 1	836
February	1st to 10th	Night	11% 31% 38% 16% 4	760
	11th to 20th	Night	11% 32% 33% 19% 4	744
	21st to end	Night	11% 32% 41% 14% 2	628
March	1st to 10th	Night	9% 29% 33% 23% 6%	742
	11th to 20th	Night	4 21% 41% 24% 10%	720
	21st to end	Night	7% 28% 41% 20% 4	714
April	1st to 10th	Night	8% 27% 38% 23% 4	540
	11th to 20th	Night	8% 28% 34% 22% 7% 1	533
	21st to end	Night	8% 21% 37% 26% 7% 1	540
May	1st to 10th	Night	7% 14% 42% 26% 11%	540
	11th to 20th	Night	8% 10% 30% 34% 16% 2	531
	21st to end	Night	8% 13% 28% 33% 16% 2	584
June	1st to 10th	Night	5% 8% 27% 36% 23% 1	540
	11th to 20th	Night	7% 11% 30% 37% 14% 1	540
	21st to end	Night	2 5% 23% 38% 29% 2	540
July	1st to 10th	Night	6% 2 14% 39% 34% 4	525
	11th to 20th	Night	3 1 12% 38% 42% 4	522
	21st to end	Night	7% 2 10% 34% 43% 5%	591
August	1st to 10th	Night	8% 1 11% 39% 37% 3	537
	11th to 20th	Night	6% 4 14% 37% 36% 4	534
	21st to end	Night	4 3 15% 39% 35% 4	594
September	1st to 10th	Night	5% 3 17% 43% 26% 5%	540
	11th to 20th	Night	7% 5% 19% 43% 23% 3	540
	21st to end	Night	4 10% 26% 32% 23% 4	611
October	1st to 10th	Night	5% 17% 30% 28% 16% 4	720
	11th to 20th	Night	8% 20% 32% 26% 13% 2	720
	21st to end	Night	7% 21% 33% 26% 11% 2	792
November	1st to 10th	Night	8% 23% 36% 24% 9% 1	887
	11th to 20th	Night	11% 27% 34% 20% 6% 2	950
	21st to end	Night	7% 24% 32% 28% 8%	950
December	1st to 10th	Night	10% 31% 35% 18% 6%	950
	11th to 20th	Night	11% 29% 35% 19% 6%	950
	21st to end	Night	13% 29% 34% 19% 4 1	1045

Page generated at 2024-03-03 04:29:00. Version ac07

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