The Cowpasture
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the The Cowpasture clear sky chart from 2005-11-06 to 2024-02-15.

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	12% 6% 3 5% 5% 3 5% 5% 6% 8% 43%	78521
	Night	12% 6% 2 4 4 3 4 4 5% 7% 48%	80573
Transparency	Day	39% 6% 11% 20% 19% 6%	78250
	Night	35% 5% 11% 20% 21% 8%	80365
Seeing	Day	14% 7% 20% 25% 23% 11%	14003
	Night	14% 7% 23% 31% 22% 4	23897

By Month

Percentage Cloud Cover SE (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	17% 12% 3 5% 3 2 3 3 5% 6% 42%	2847
	11th to 20th	Day	17% 6% 3 5% 4 2 3 4 4 5% 48%	2850
	21st to end	Day	22% 8% 3 5% 4 2 3 3 3 5% 41%	3162
February	1st to 10th	Day	17% 9% 3 5% 5% 2 4 4 5% 6% 40%	1900
	11th to 20th	Day	20% 9% 3 5% 4 3 2 4 4 5% 41%	1788
	21st to end	Day	19% 7% 4 8% 5% 3 4 4 4 5% 38%	1480
March	1st to 10th	Day	16% 6% 3 7% 4 3 5% 4 4 7% 42%	1898
	11th to 20th	Day	15% 7% 4 6% 5% 3 6% 4 6% 7% 37%	1980
	21st to end	Day	10% 7% 3 7% 6% 4 4 4 6% 7% 42%	2267
April	1st to 10th	Day	12% 4 3 6% 4 3 5% 5% 6% 7% 45%	2160
	11th to 20th	Day	15% 5% 3 7% 5% 3 4 4 5% 7% 43%	2134
	21st to end	Day	9% 4 3 4 6% 3 5% 5% 6% 8% 48%	2160
May	1st to 10th	Day	10% 5% 3 6% 6% 3 6% 5% 5% 9% 43%	2160
	11th to 20th	Day	10% 6% 2 5% 5% 4 5% 6% 6% 9% 43%	2124
	21st to end	Day	8% 4 2 5% 6% 4 6% 7% 7% 9% 42%	2377
June	1st to 10th	Day	9% 5% 3 5% 7% 4 7% 7% 7% 9% 38%	2520
	11th to 20th	Day	4 4 2 7% 7% 4 6% 7% 7% 9% 43%	2520
	21st to end	Day	6% 4 2 5% 7% 4 7% 7% 8% 10% 40%	2419
July	1st to 10th	Day	6% 5% 3 6% 7% 4 8% 8% 8% 11% 32%	2340
	11th to 20th	Day	8% 4 3 6% 7% 4 7% 9% 8% 11% 32%	2340
	21st to end	Day	8% 4 3 6% 6% 5% 7% 8% 9% 11% 33%	2488
August	1st to 10th	Day	6% 3 2 6% 6% 4 6% 6% 9% 11% 41%	2148
	11th to 20th	Day	8% 5% 3 7% 6% 5% 7% 7% 7% 10% 36%	2125
	21st to end	Day	13% 4 2 4 5% 4 5% 6% 7% 9% 41%	2376
September	1st to 10th	Day	8% 4 2 6% 7% 3 6% 7% 6% 9% 41%	2160
	11th to 20th	Day	12% 6% 3 5% 5% 3 4 5% 5% 7% 44%	2130
	21st to end	Day	11% 4 2 4 4 2 4 4 5% 7% 54%	1980
October	1st to 10th	Day	7% 3 2 5% 4 3 5% 4 5% 6% 58%	1837
	11th to 20th	Day	10% 4 2 5% 4 2 4 3 5% 6% 55%	1800
	21st to end	Day	14% 4 2 3 4 2 3 4 3 5% 57%	1980
November	1st to 10th	Day	10% 4 2 4 4 2 4 3 4 6% 55%	1858
	11th to 20th	Day	12% 5% 3 4 5% 2 4 4 4 6% 52%	1751
	21st to end	Day	17% 6% 2 5% 4 2 4 4 5% 5% 47%	1710
December	1st to 10th	Day	17% 8% 2 5% 5% 3 3 4 4 7% 42%	1710
	11th to 20th	Day	15% 10% 4 6% 5% 3 4 3 4 6% 41%	2035
	21st to end	Day	15% 7% 2 5% 4 2 4 4 6% 7% 44%	3007
January	1st to 10th	Night	18% 9% 2 4 4 2 3 4 4 5% 45%	4108
	11th to 20th	Night	15% 7% 3 5% 4 2 3 4 4 6% 48%	4120
	21st to end	Night	24% 9% 3 4 3 2 2 3 3 4 43%	4500
February	1st to 10th	Night	17% 8% 4 5% 5% 2 3 4 4 6% 42%	2280
	11th to 20th	Night	20% 6% 3 4 4 2 3 4 4 5% 46%	2153
	21st to end	Night	22% 7% 3 5% 5% 2 3 4 5% 5% 39%	1776
March	1st to 10th	Night	14% 7% 2 5% 5% 3 4 3 5% 7% 47%	2075
	11th to 20th	Night	14% 6% 3 6% 6% 3 5% 5% 5% 7% 40%	1980
	21st to end	Night	13% 5% 2 4 5% 3 4 4 6% 6% 48%	2088
April	1st to 10th	Night	11% 5% 2 4 3 3 5% 5% 6% 8% 48%	1800
	11th to 20th	Night	12% 5% 2 4 5% 3 4 4 6% 7% 48%	1775
	21st to end	Night	7% 3 2 5% 5% 3 4 4 5% 8% 54%	1800
May	1st to 10th	Night	8% 4 1 4 4 2 4 4 6% 10% 53%	1800
	11th to 20th	Night	8% 5% 2 5% 4 2 5% 5% 6% 10% 47%	1769
	21st to end	Night	6% 3 2 4 4 3 5% 5% 7% 12% 49%	1889
June	1st to 10th	Night	5% 6% 2 4 6% 4 5% 6% 6% 9% 46%	1440
	11th to 20th	Night	3 3 2 3 3 3 4 6% 8% 12% 53%	1440
	21st to end	Night	4 4 3 4 4 3 6% 6% 7% 11% 48%	1532
July	1st to 10th	Night	6% 4 2 5% 5% 3 5% 5% 8% 12% 45%	1620
	11th to 20th	Night	5% 4 1 5% 6% 4 5% 5% 7% 11% 46%	1620
	21st to end	Night	4 3 2 5% 4 3 5% 6% 7% 13% 48%	1829
August	1st to 10th	Night	2 3 2 3 4 3 5% 6% 9% 13% 51%	1790
	11th to 20th	Night	6% 4 2 5% 4 3 5% 6% 8% 13% 43%	1776
	21st to end	Night	10% 4 2 5% 5% 3 5% 5% 7% 10% 45%	1980
September	1st to 10th	Night	9% 4 3 4 5% 3 4 5% 6% 10% 47%	1800
	11th to 20th	Night	8% 4 2 5% 4 4 5% 5% 7% 8% 48%	1809
	21st to end	Night	9% 4 2 4 4 2 3 4 5% 7% 56%	1980
October	1st to 10th	Night	6% 3 2 3 3 2 3 4 4 7% 63%	2117
	11th to 20th	Night	11% 4 2 4 4 2 3 5% 4 5% 55%	2160
	21st to end	Night	14% 5% 2 4 4 2 3 2 3 5% 57%	2376
November	1st to 10th	Night	12% 5% 1 3 3 2 3 3 3 6% 59%	2220
	11th to 20th	Night	13% 5% 2 4 3 2 3 4 4 6% 55%	2425
	21st to end	Night	13% 6% 2 4 4 3 4 5% 5% 6% 49%	2470
December	1st to 10th	Night	17% 5% 2 5% 4 3 4 4 4 6% 45%	2470
	11th to 20th	Night	15% 7% 3 5% 5% 3 4 3 4 5% 46%	3150
	21st to end	Night	16% 10% 3 5% 4 2 3 4 5% 5% 42%	4656

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	44% 3 4 17% 26% 5%	2848
	11th to 20th	Day	38% 4 8% 22% 22% 6%	2850
	21st to end	Day	48% 2 5% 14% 22% 8%	3162
February	1st to 10th	Day	46% 4 7% 17% 17% 9%	1900
	11th to 20th	Day	46% 3 6% 18% 19% 8%	1798
	21st to end	Day	50% 3 5% 13% 19% 9%	1480
March	1st to 10th	Day	43% 4 8% 15% 20% 9%	1898
	11th to 20th	Day	46% 6% 8% 15% 18% 6%	1980
	21st to end	Day	41% 5% 8% 20% 21% 4	2267
April	1st to 10th	Day	37% 5% 9% 24% 18% 7%	2160
	11th to 20th	Day	42% 3 7% 18% 24% 6%	2134
	21st to end	Day	35% 4 8% 26% 24% 2	2160
May	1st to 10th	Day	38% 7% 10% 20% 20% 5%	2160
	11th to 20th	Day	38% 5% 14% 26% 16% 1	2128
	21st to end	Day	34% 8% 17% 25% 15% 1	2377
June	1st to 10th	Day	39% 8% 15% 24% 12% 2	2520
	11th to 20th	Day	35% 7% 17% 24% 14% 3	2520
	21st to end	Day	36% 9% 17% 22% 14% 2	2419
July	1st to 10th	Day	40% 12% 20% 20% 7% 1	2276
	11th to 20th	Day	38% 12% 23% 19% 6% 2	2271
	21st to end	Day	39% 11% 19% 21% 9% 1	2350
August	1st to 10th	Day	34% 9% 23% 27% 7%	2136
	11th to 20th	Day	41% 10% 18% 18% 10% 3	2125
	21st to end	Day	39% 8% 18% 20% 11% 4	2376
September	1st to 10th	Day	38% 8% 14% 18% 17% 6%	2160
	11th to 20th	Day	39% 6% 10% 17% 20% 8%	2130
	21st to end	Day	30% 4 12% 24% 20% 11%	1980
October	1st to 10th	Day	27% 4 9% 22% 25% 13%	1837
	11th to 20th	Day	30% 4 6% 17% 30% 13%	1800
	21st to end	Day	33% 3 4 17% 31% 12%	1980
November	1st to 10th	Day	32% 3 6% 18% 30% 11%	1858
	11th to 20th	Day	35% 3 5% 15% 28% 13%	1751
	21st to end	Day	40% 4 6% 18% 22% 10%	1710
December	1st to 10th	Day	43% 3 10% 18% 17% 9%	1710
	11th to 20th	Day	46% 3 6% 16% 23% 6%	2032
	21st to end	Day	39% 5% 6% 20% 27% 3	3007
January	1st to 10th	Night	43% 3 5% 15% 26% 8%	4108
	11th to 20th	Night	38% 4 6% 20% 20% 11%	4120
	21st to end	Night	47% 3 5% 16% 23% 6%	4500
February	1st to 10th	Night	44% 3 6% 17% 21% 8%	2280
	11th to 20th	Night	42% 4 6% 17% 21% 10%	2154
	21st to end	Night	48% 5% 6% 14% 16% 12%	1776
March	1st to 10th	Night	37% 5% 7% 17% 21% 12%	2075
	11th to 20th	Night	43% 6% 9% 17% 17% 8%	1980
	21st to end	Night	36% 4 10% 20% 23% 6%	2088
April	1st to 10th	Night	34% 5% 12% 20% 20% 9%	1800
	11th to 20th	Night	35% 4 9% 20% 22% 9%	1775
	21st to end	Night	29% 4 9% 26% 27% 5%	1800
May	1st to 10th	Night	28% 6% 11% 27% 22% 6%	1800
	11th to 20th	Night	31% 6% 16% 26% 18% 2	1770
	21st to end	Night	27% 7% 18% 28% 17% 2	1890
June	1st to 10th	Night	33% 8% 17% 25% 16% 2	1440
	11th to 20th	Night	23% 7% 19% 30% 16% 4	1440
	21st to end	Night	29% 7% 22% 23% 17% 3	1532
July	1st to 10th	Night	31% 9% 24% 26% 8% 3	1575
	11th to 20th	Night	29% 12% 26% 24% 8% 2	1566
	21st to end	Night	25% 10% 27% 26% 11% 1	1727
August	1st to 10th	Night	21% 11% 29% 27% 12%	1778
	11th to 20th	Night	30% 12% 21% 21% 13% 3	1776
	21st to end	Night	33% 10% 19% 19% 14% 5%	1980
September	1st to 10th	Night	31% 8% 15% 22% 18% 6%	1800
	11th to 20th	Night	33% 7% 15% 15% 20% 9%	1809
	21st to end	Night	28% 5% 10% 25% 21% 11%	1980
October	1st to 10th	Night	22% 3 10% 23% 26% 16%	2117
	11th to 20th	Night	31% 5% 5% 16% 28% 15%	2160
	21st to end	Night	33% 3 6% 16% 26% 16%	2376
November	1st to 10th	Night	30% 2 6% 18% 29% 14%	2220
	11th to 20th	Night	31% 4 7% 16% 27% 15%	2425
	21st to end	Night	37% 4 7% 19% 21% 13%	2470
December	1st to 10th	Night	41% 4 10% 18% 20% 7%	2470
	11th to 20th	Night	43% 3 6% 13% 27% 8%	3152
	21st to end	Night	44% 3 6% 17% 25% 5%	4656

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	23% 19% 39% 15% 3 1	270
	11th to 20th	Day	26% 19% 33% 15% 7%	270
	21st to end	Day	27% 20% 35% 15% 3	297
February	1st to 10th	Day	23% 20% 37% 14% 6% 1	270
	11th to 20th	Day	35% 11% 38% 13% 2	252
	21st to end	Day	25% 22% 39% 13% 1	198
March	1st to 10th	Day	25% 17% 37% 18% 3	240
	11th to 20th	Day	23% 20% 36% 18% 4	240
	21st to end	Day	18% 17% 34% 22% 8%	353
April	1st to 10th	Day	15% 15% 34% 25% 10% 1	420
	11th to 20th	Day	23% 12% 26% 26% 10% 2	412
	21st to end	Day	12% 9% 30% 32% 15% 1	420
May	1st to 10th	Day	13% 10% 27% 32% 15% 3	423
	11th to 20th	Day	13% 3 21% 30% 22% 10%	447
	21st to end	Day	6% 3 19% 31% 28% 13%	485
June	1st to 10th	Day	11% 4 13% 29% 30% 13%	630
	11th to 20th	Day	6% 3 13% 33% 33% 12%	630
	21st to end	Day	9% 2 12% 29% 31% 18%	630
July	1st to 10th	Day	5% 1 7% 29% 37% 21%	621
	11th to 20th	Day	6% 2 4 19% 40% 28%	618
	21st to end	Day	8% 7% 23% 38% 24%	626
August	1st to 10th	Day	7% 1 7% 19% 36% 30%	446
	11th to 20th	Day	7% 1 6% 20% 41% 25%	439
	21st to end	Day	16% 1 6% 16% 34% 27%	495
September	1st to 10th	Day	7% 1 9% 25% 39% 19%	450
	11th to 20th	Day	12% 2 11% 20% 36% 20%	450
	21st to end	Day	12% 2 10% 31% 32% 13%	450
October	1st to 10th	Day	9% 2 20% 37% 21% 10%	307
	11th to 20th	Day	10% 6% 24% 37% 18% 5%	270
	21st to end	Day	22% 9% 24% 26% 15% 4	297
November	1st to 10th	Day	17% 6% 24% 36% 14% 4	270
	11th to 20th	Day	14% 14% 35% 24% 11% 1	270
	21st to end	Day	18% 14% 36% 18% 11% 3	270
December	1st to 10th	Day	23% 15% 34% 20% 7% 1	270
	11th to 20th	Day	21% 14% 34% 24% 6% 1	270
	21st to end	Day	23% 16% 35% 21% 5%	297
January	1st to 10th	Night	23% 12% 32% 28% 5%	950
	11th to 20th	Night	20% 12% 33% 26% 8%	950
	21st to end	Night	23% 12% 34% 28% 4	1026
February	1st to 10th	Night	21% 13% 33% 29% 4	760
	11th to 20th	Night	24% 13% 31% 28% 5%	722
	21st to end	Night	26% 14% 35% 24% 2	592
March	1st to 10th	Night	18% 12% 33% 31% 6%	635
	11th to 20th	Night	17% 9% 37% 29% 7% 1	540
	21st to end	Night	16% 9% 37% 30% 8%	594
April	1st to 10th	Night	14% 9% 36% 30% 11% 1	540
	11th to 20th	Night	14% 10% 31% 32% 12% 1	533
	21st to end	Night	7% 7% 35% 36% 14%	540
May	1st to 10th	Night	10% 5% 26% 42% 15% 2	540
	11th to 20th	Night	9% 2 22% 40% 23% 3	531
	21st to end	Night	5% 2 16% 35% 34% 7%	584
June	1st to 10th	Night	9% 1 10% 38% 38% 5%	540
	11th to 20th	Night	4 1 8% 34% 45% 7%	540
	21st to end	Night	4 1 10% 29% 43% 13%	540
July	1st to 10th	Night	5% 1 6% 29% 48% 11%	525
	11th to 20th	Night	4 1 5% 24% 49% 18%	522
	21st to end	Night	4 1 5% 27% 49% 14%	591
August	1st to 10th	Night	3 1 4 23% 51% 19%	537
	11th to 20th	Night	8% 4 22% 52% 14%	534
	21st to end	Night	11% 1 6% 22% 46% 15%	594
September	1st to 10th	Night	9% 1 9% 28% 45% 9%	540
	11th to 20th	Night	9% 2 8% 29% 43% 9%	549
	21st to end	Night	12% 1 10% 34% 38% 6%	720
October	1st to 10th	Night	7% 2 15% 38% 32% 7%	720
	11th to 20th	Night	14% 5% 21% 35% 24% 2	720
	21st to end	Night	17% 6% 20% 34% 20% 3	792
November	1st to 10th	Night	14% 6% 18% 39% 21% 2	740
	11th to 20th	Night	14% 7% 29% 35% 14% 1	760
	21st to end	Night	15% 8% 28% 34% 14% 2	760
December	1st to 10th	Night	19% 9% 31% 32% 9%	760
	11th to 20th	Night	20% 9% 30% 32% 9%	831
	21st to end	Night	24% 11% 30% 28% 7%	1045

Page generated at 2024-02-12 05:35:36. Version ac07

Copyright 2024 Attilla Danko