Wardrop Ranch
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Wardrop Ranch clear sky chart from 2005-11-06 to 2024-01-16.

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	5% 5% 2 4 4 3 4 5% 6% 8% 55%	74816
	Night	5% 5% 2 4 4 3 4 4 5% 8% 56%	75007
Transparency	Day	26% 7% 12% 23% 23% 10%	74521
	Night	26% 6% 12% 24% 23% 9%	74824
Seeing	Day	7% 10% 29% 30% 19% 6%	14419
	Night	6% 6% 35% 39% 13% 1	24570

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 5% 2 4 3 2 2 3 5% 8% 65%	1518
	11th to 20th	Day	4 5% 3 6% 3 3 3 3 4 7% 60%	1498
	21st to end	Day	2 6% 3 4 4 2 4 3 4 7% 60%	1782
February	1st to 10th	Day	2 7% 3 6% 4 2 4 4 4 8% 57%	1651
	11th to 20th	Day	1 4 3 5% 5% 4 5% 3 6% 6% 58%	1749
	21st to end	Day	3 6% 3 6% 5% 3 3 3 4 6% 57%	1480
March	1st to 10th	Day	4 6% 3 4 5% 2 4 5% 5% 7% 56%	1800
	11th to 20th	Day	6% 7% 3 4 3 2 4 3 4 7% 58%	1908
	21st to end	Day	5% 9% 3 4 4 3 4 4 6% 8% 51%	2340
April	1st to 10th	Day	6% 6% 1 3 4 3 5% 5% 6% 7% 54%	2160
	11th to 20th	Day	6% 8% 3 5% 4 3 4 5% 6% 8% 47%	2131
	21st to end	Day	9% 7% 2 4 5% 3 5% 5% 6% 8% 46%	2160
May	1st to 10th	Day	9% 8% 3 6% 4 3 5% 5% 6% 9% 42%	2299
	11th to 20th	Day	11% 7% 2 5% 5% 3 5% 5% 7% 9% 41%	2399
	21st to end	Day	7% 4 2 4 4 4 5% 6% 7% 9% 47%	2724
June	1st to 10th	Day	6% 3 2 4 4 3 4 6% 7% 9% 52%	2520
	11th to 20th	Day	6% 4 1 3 4 3 5% 6% 7% 10% 53%	2520
	21st to end	Day	4 3 2 4 5% 3 6% 7% 7% 10% 51%	2520
July	1st to 10th	Day	6% 3 2 4 4 3 6% 7% 8% 10% 48%	2520
	11th to 20th	Day	3 3 2 4 4 3 6% 5% 7% 10% 52%	2520
	21st to end	Day	6% 3 3 5% 5% 4 6% 7% 8% 10% 44%	2730
August	1st to 10th	Day	6% 3 1 5% 5% 4 6% 8% 7% 11% 42%	2279
	11th to 20th	Day	5% 2 1 3 4 2 5% 5% 8% 9% 57%	2123
	21st to end	Day	4 2 1 3 4 3 5% 5% 7% 9% 54%	2376
September	1st to 10th	Day	4 3 1 3 4 3 4 4 6% 8% 60%	2160
	11th to 20th	Day	6% 2 1 3 3 2 3 4 6% 8% 61%	2110
	21st to end	Day	5% 3 1 2 3 3 3 4 4 6% 66%	1980
October	1st to 10th	Day	6% 4 1 3 2 2 4 4 5% 6% 63%	1868
	11th to 20th	Day	5% 2 1 3 3 1 3 3 3 6% 71%	1800
	21st to end	Day	6% 5% 2 3 2 2 3 2 3 5% 66%	1886
November	1st to 10th	Day	1 3 1 2 3 2 4 4 5% 7% 67%	1673
	11th to 20th	Day	2 5% 2 4 3 2 4 3 4 5% 65%	1710
	21st to end	Day	3 5% 3 4 4 2 2 3 4 6% 64%	1682
December	1st to 10th	Day	2 5% 2 3 5% 2 4 5% 5% 8% 59%	1520
	11th to 20th	Day	2 5% 3 4 4 3 4 5% 7% 9% 56%	1926
	21st to end	Day	3 7% 3 7% 5% 3 4 4 4 7% 53%	2794
January	1st to 10th	Night	2 6% 2 4 4 2 3 3 4 7% 63%	2647
	11th to 20th	Night	3 5% 2 4 4 2 4 4 4 7% 61%	2599
	21st to end	Night	2 5% 3 5% 5% 3 5% 4 4 6% 57%	2574
February	1st to 10th	Night	2 7% 3 6% 4 2 3 3 4 8% 58%	2308
	11th to 20th	Night	2 7% 4 6% 5% 3 4 5% 5% 7% 52%	2098
	21st to end	Night	3 7% 3 5% 4 2 3 3 5% 5% 60%	1776
March	1st to 10th	Night	3 5% 2 4 5% 2 4 4 6% 8% 57%	2160
	11th to 20th	Night	6% 7% 2 4 4 2 4 4 5% 7% 55%	2048
	21st to end	Night	4 8% 2 4 3 3 3 5% 5% 9% 54%	2015
April	1st to 10th	Night	6% 7% 2 4 4 3 4 4 6% 7% 54%	1800
	11th to 20th	Night	9% 9% 2 5% 4 3 3 5% 5% 7% 47%	1777
	21st to end	Night	11% 8% 2 4 5% 3 4 4 5% 7% 47%	1800
May	1st to 10th	Night	10% 8% 2 5% 5% 3 4 5% 5% 7% 46%	1659
	11th to 20th	Night	13% 6% 1 4 3 3 5% 5% 7% 8% 44%	1492
	21st to end	Night	10% 4 2 3 5% 4 5% 4 5% 9% 49%	1552
June	1st to 10th	Night	5% 4 1 3 3 3 4 6% 5% 13% 54%	1440
	11th to 20th	Night	5% 3 2 3 4 3 4 4 6% 8% 59%	1440
	21st to end	Night	5% 4 2 4 5% 2 4 6% 6% 10% 53%	1440
July	1st to 10th	Night	8% 4 2 4 5% 3 5% 7% 7% 10% 46%	1440
	11th to 20th	Night	3 2 2 5% 5% 3 6% 6% 7% 10% 53%	1440
	21st to end	Night	6% 3 1 5% 5% 3 6% 7% 9% 10% 44%	1584
August	1st to 10th	Night	5% 5% 2 5% 5% 4 7% 6% 7% 12% 43%	1659
	11th to 20th	Night	6% 3 2 4 4 3 4 6% 8% 9% 51%	1778
	21st to end	Night	4 3 2 4 4 3 5% 5% 6% 9% 54%	1980
September	1st to 10th	Night	6% 4 2 4 4 3 3 4 6% 8% 55%	1800
	11th to 20th	Night	6% 3 1 3 3 2 3 4 5% 9% 62%	1849
	21st to end	Night	6% 3 2 3 4 2 3 4 5% 7% 63%	1980
October	1st to 10th	Night	8% 5% 2 3 4 2 3 4 5% 7% 58%	2088
	11th to 20th	Night	3 2 1 3 3 2 2 4 4 7% 69%	2160
	21st to end	Night	5% 5% 2 4 4 2 2 3 3 6% 64%	2452
November	1st to 10th	Night	2 3 1 3 3 2 3 4 5% 8% 67%	2405
	11th to 20th	Night	2 5% 2 4 3 2 3 3 4 6% 67%	2470
	21st to end	Night	4 6% 3 5% 3 3 3 3 5% 7% 59%	2493
December	1st to 10th	Night	2 4 3 4 4 3 3 4 4 7% 61%	2660
	11th to 20th	Night	2 5% 3 4 5% 3 4 4 6% 8% 58%	3271
	21st to end	Night	4 7% 3 5% 5% 3 4 5% 5% 6% 53%	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	18% 4 13% 30% 28% 8%	1519
	11th to 20th	Day	25% 4 10% 28% 26% 8%	1498
	21st to end	Day	24% 4 9% 31% 23% 9%	1782
February	1st to 10th	Day	27% 4 12% 28% 19% 10%	1651
	11th to 20th	Day	25% 5% 9% 27% 26% 8%	1759
	21st to end	Day	28% 4 8% 23% 25% 12%	1480
March	1st to 10th	Day	26% 5% 10% 23% 25% 10%	1800
	11th to 20th	Day	28% 5% 10% 26% 26% 7%	1908
	21st to end	Day	31% 7% 13% 23% 19% 7%	2340
April	1st to 10th	Day	28% 6% 14% 21% 22% 9%	2160
	11th to 20th	Day	32% 7% 13% 22% 18% 8%	2134
	21st to end	Day	33% 7% 13% 25% 20% 3	2160
May	1st to 10th	Day	37% 8% 13% 23% 15% 4	2299
	11th to 20th	Day	36% 9% 15% 23% 14% 2	2403
	21st to end	Day	29% 10% 15% 25% 14% 7%	2724
June	1st to 10th	Day	26% 8% 17% 23% 17% 10%	2520
	11th to 20th	Day	24% 7% 13% 18% 23% 15%	2520
	21st to end	Day	24% 8% 13% 20% 24% 11%	2520
July	1st to 10th	Day	28% 10% 13% 17% 21% 11%	2451
	11th to 20th	Day	23% 9% 12% 23% 23% 9%	2445
	21st to end	Day	30% 11% 18% 23% 14% 5%	2578
August	1st to 10th	Day	31% 11% 17% 20% 14% 6%	2264
	11th to 20th	Day	22% 6% 12% 24% 24% 11%	2123
	21st to end	Day	23% 7% 11% 23% 26% 10%	2376
September	1st to 10th	Day	21% 5% 9% 22% 25% 17%	2160
	11th to 20th	Day	20% 6% 11% 18% 28% 18%	2110
	21st to end	Day	20% 4 8% 20% 36% 12%	1980
October	1st to 10th	Day	21% 6% 10% 21% 29% 12%	1868
	11th to 20th	Day	17% 3 8% 25% 33% 15%	1800
	21st to end	Day	22% 4 8% 26% 26% 15%	1886
November	1st to 10th	Day	17% 3 11% 25% 27% 17%	1673
	11th to 20th	Day	21% 4 6% 25% 34% 9%	1710
	21st to end	Day	23% 3 8% 21% 28% 16%	1682
December	1st to 10th	Day	23% 5% 11% 29% 24% 8%	1520
	11th to 20th	Day	23% 7% 12% 22% 29% 7%	1924
	21st to end	Day	27% 7% 10% 24% 24% 8%	2794
January	1st to 10th	Night	22% 4 11% 27% 28% 7%	2647
	11th to 20th	Night	23% 4 10% 25% 27% 10%	2599
	21st to end	Night	27% 5% 9% 28% 24% 7%	2574
February	1st to 10th	Night	27% 4 11% 28% 22% 8%	2308
	11th to 20th	Night	31% 5% 10% 26% 21% 7%	2098
	21st to end	Night	25% 4 7% 26% 25% 13%	1776
March	1st to 10th	Night	24% 6% 11% 23% 26% 9%	2160
	11th to 20th	Night	27% 6% 11% 22% 28% 6%	2048
	21st to end	Night	28% 6% 12% 25% 25% 4	2015
April	1st to 10th	Night	29% 6% 12% 23% 21% 10%	1800
	11th to 20th	Night	34% 6% 13% 23% 17% 6%	1777
	21st to end	Night	36% 7% 12% 24% 17% 4	1800
May	1st to 10th	Night	36% 9% 15% 22% 15% 3	1659
	11th to 20th	Night	35% 10% 19% 22% 10% 4	1493
	21st to end	Night	31% 9% 19% 23% 11% 7%	1552
June	1st to 10th	Night	23% 8% 22% 26% 14% 7%	1440
	11th to 20th	Night	22% 7% 15% 23% 20% 14%	1440
	21st to end	Night	23% 8% 12% 26% 21% 8%	1440
July	1st to 10th	Night	31% 11% 17% 19% 17% 6%	1400
	11th to 20th	Night	23% 9% 15% 29% 18% 7%	1392
	21st to end	Night	28% 13% 20% 21% 16% 1	1496
August	1st to 10th	Night	31% 12% 19% 22% 11% 5%	1650
	11th to 20th	Night	26% 6% 14% 29% 19% 6%	1778
	21st to end	Night	23% 8% 14% 27% 21% 8%	1980
September	1st to 10th	Night	26% 7% 11% 20% 25% 12%	1800
	11th to 20th	Night	19% 7% 11% 23% 25% 15%	1849
	21st to end	Night	21% 5% 10% 23% 31% 10%	1980
October	1st to 10th	Night	26% 7% 11% 19% 25% 11%	2088
	11th to 20th	Night	15% 5% 10% 25% 29% 16%	2160
	21st to end	Night	23% 3 9% 26% 25% 14%	2452
November	1st to 10th	Night	16% 4 11% 24% 28% 17%	2405
	11th to 20th	Night	20% 3 9% 27% 31% 10%	2470
	21st to end	Night	25% 4 8% 21% 29% 12%	2493
December	1st to 10th	Night	22% 5% 13% 26% 25% 9%	2660
	11th to 20th	Night	23% 5% 10% 23% 32% 7%	3272
	21st to end	Night	28% 6% 10% 24% 24% 8%	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	5% 5% 32% 39% 16% 4	270
	11th to 20th	Day	8% 13% 29% 38% 11% 1	255
	21st to end	Day	3 11% 43% 32% 10% 1	264
February	1st to 10th	Day	4 13% 46% 28% 7% 2	240
	11th to 20th	Day	3 13% 45% 30% 8% 1	240
	21st to end	Day	3 16% 42% 29% 9% 1	198
March	1st to 10th	Day	4 15% 34% 31% 13% 3	240
	11th to 20th	Day	11% 15% 38% 26% 9% 1	348
	21st to end	Day	14% 21% 35% 20% 8% 1	462
April	1st to 10th	Day	9% 19% 37% 24% 9% 2	420
	11th to 20th	Day	14% 25% 31% 21% 8% 1	412
	21st to end	Day	13% 19% 34% 22% 10% 2	420
May	1st to 10th	Day	11% 16% 32% 27% 10% 3	562
	11th to 20th	Day	13% 9% 29% 30% 15% 4	625
	21st to end	Day	9% 13% 28% 26% 18% 6%	679
June	1st to 10th	Day	6% 8% 25% 28% 24% 9%	630
	11th to 20th	Day	5% 10% 29% 33% 19% 4	630
	21st to end	Day	4 6% 25% 35% 24% 7%	630
July	1st to 10th	Day	7% 4 15% 34% 31% 9%	621
	11th to 20th	Day	4 2 15% 33% 34% 12%	618
	21st to end	Day	5% 1 15% 31% 35% 13%	672
August	1st to 10th	Day	7% 2 19% 33% 26% 13%	447
	11th to 20th	Day	4 3 20% 36% 24% 13%	437
	21st to end	Day	5% 3 25% 32% 27% 8%	495
September	1st to 10th	Day	5% 4 24% 32% 25% 10%	450
	11th to 20th	Day	5% 5% 28% 29% 24% 11%	400
	21st to end	Day	7% 5% 21% 29% 26% 12%	270
October	1st to 10th	Day	7% 11% 21% 24% 21% 15%	270
	11th to 20th	Day	2 9% 30% 30% 20% 8%	270
	21st to end	Day	8% 9% 33% 30% 14% 5%	297
November	1st to 10th	Day	2 10% 31% 33% 19% 5%	270
	11th to 20th	Day	5% 9% 30% 40% 13% 3	270
	21st to end	Day	4 10% 34% 35% 14% 3	270
December	1st to 10th	Day	4 13% 41% 27% 14% 2	270
	11th to 20th	Day	4 9% 40% 36% 10% 1	270
	21st to end	Day	7% 12% 37% 31% 12% 1	297
January	1st to 10th	Night	4 4 38% 41% 10% 2	950
	11th to 20th	Night	5% 8% 39% 38% 9% 2	926
	21st to end	Night	4 5% 40% 42% 9% 1	792
February	1st to 10th	Night	4 6% 49% 36% 5% 1	720
	11th to 20th	Night	5% 7% 48% 34% 6% 1	704
	21st to end	Night	5% 8% 48% 34% 5%	592
March	1st to 10th	Night	5% 8% 44% 35% 8% 1	720
	11th to 20th	Night	8% 7% 40% 36% 9%	720
	21st to end	Night	8% 9% 43% 33% 7%	629
April	1st to 10th	Night	10% 9% 46% 29% 6%	540
	11th to 20th	Night	13% 12% 39% 29% 7%	533
	21st to end	Night	15% 10% 34% 32% 8%	540
May	1st to 10th	Night	13% 8% 32% 38% 9% 1	540
	11th to 20th	Night	16% 5% 30% 36% 12% 1	531
	21st to end	Night	11% 7% 35% 33% 13% 1	584
June	1st to 10th	Night	6% 4 29% 42% 18% 2	540
	11th to 20th	Night	5% 3 36% 43% 13%	540
	21st to end	Night	4 2 28% 46% 19% 1	540
July	1st to 10th	Night	7% 2 21% 43% 26% 2	525
	11th to 20th	Night	3 19% 49% 26% 3	522
	21st to end	Night	7% 2 13% 43% 34% 1	591
August	1st to 10th	Night	6% 1 19% 47% 25% 2	537
	11th to 20th	Night	5% 2 22% 50% 19% 1	534
	21st to end	Night	5% 2 19% 48% 22% 3	594
September	1st to 10th	Night	6% 1 24% 47% 19% 3	540
	11th to 20th	Night	7% 2 24% 45% 19% 2	540
	21st to end	Night	5% 4 25% 46% 16% 3	540
October	1st to 10th	Night	10% 5% 35% 32% 15% 3	648
	11th to 20th	Night	4 4 32% 43% 14% 3	720
	21st to end	Night	7% 7% 32% 35% 16% 2	868
November	1st to 10th	Night	3 6% 35% 41% 14% 2	925
	11th to 20th	Night	4 7% 38% 40% 10% 1	950
	21st to end	Night	7% 8% 33% 38% 12% 2	950
December	1st to 10th	Night	3 7% 40% 39% 10% 1	950
	11th to 20th	Night	5% 6% 42% 35% 11% 1	950
	21st to end	Night	6% 9% 40% 36% 7% 1	1045

Page generated at 2024-01-13 07:37:57. Version ac07

Copyright 2024 Attilla Danko