Wray
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Wray clear sky chart from 2005-11-06 to 2024-01-12.

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	7% 5% 2 4 4 2 4 4 5% 8% 56%	74841
	Night	7% 5% 2 4 4 3 4 4 5% 7% 54%	74894
Transparency	Day	27% 6% 12% 27% 22% 7%	74546
	Night	29% 6% 12% 26% 21% 7%	74712
Seeing	Day	10% 6% 26% 32% 20% 5%	14504
	Night	9% 6% 33% 40% 11% 1	24596

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	5% 5% 3 4 3 1 3 4 5% 8% 60%	1518
	11th to 20th	Day	5% 7% 3 4 3 2 4 4 5% 6% 57%	1448
	21st to end	Day	4 6% 3 5% 5% 3 3 4 4 7% 56%	1639
February	1st to 10th	Day	5% 7% 4 6% 6% 3 6% 5% 4 7% 49%	1775
	11th to 20th	Day	4 8% 3 5% 5% 3 5% 5% 4 7% 51%	1749
	21st to end	Day	4 8% 3 5% 4 2 3 3 4 7% 56%	1480
March	1st to 10th	Day	5% 6% 3 3 4 2 4 3 4 8% 57%	1800
	11th to 20th	Day	8% 7% 2 3 3 3 4 4 4 6% 56%	1862
	21st to end	Day	9% 7% 3 6% 4 3 4 4 6% 7% 48%	2330
April	1st to 10th	Day	9% 5% 2 4 4 2 4 4 5% 8% 54%	2160
	11th to 20th	Day	13% 4 2 4 4 3 3 4 5% 9% 49%	2131
	21st to end	Day	11% 7% 2 4 4 3 4 5% 6% 7% 48%	2263
May	1st to 10th	Day	13% 4 2 4 4 3 4 5% 5% 7% 47%	2340
	11th to 20th	Day	13% 4 2 4 3 3 4 5% 5% 9% 47%	2302
	21st to end	Day	10% 4 2 4 4 2 4 5% 6% 9% 50%	2690
June	1st to 10th	Day	6% 2 1 3 3 2 3 5% 7% 9% 58%	2520
	11th to 20th	Day	7% 3 2 3 3 3 4 5% 6% 8% 58%	2520
	21st to end	Day	4 2 2 3 4 2 4 6% 7% 9% 59%	2520
July	1st to 10th	Day	6% 4 1 3 4 3 4 5% 7% 9% 56%	2520
	11th to 20th	Day	3 2 1 2 3 2 4 5% 7% 11% 60%	2520
	21st to end	Day	5% 3 2 4 4 2 5% 5% 6% 10% 54%	2742
August	1st to 10th	Day	7% 3 2 3 4 3 5% 5% 7% 9% 51%	2342
	11th to 20th	Day	5% 3 2 3 3 2 5% 4 5% 8% 59%	2133
	21st to end	Day	5% 3 1 3 3 3 4 3 4 7% 64%	2376
September	1st to 10th	Day	6% 4 2 3 3 2 3 4 4 7% 62%	2160
	11th to 20th	Day	7% 3 1 2 3 2 3 4 4 7% 63%	2016
	21st to end	Day	9% 3 1 2 2 2 2 3 4 6% 66%	1980
October	1st to 10th	Day	13% 3 1 3 3 2 3 3 3 5% 60%	1980
	11th to 20th	Day	7% 4 1 2 3 1 3 3 4 6% 66%	1810
	21st to end	Day	8% 6% 2 3 3 2 2 2 3 6% 63%	1782
November	1st to 10th	Day	3 3 1 4 4 2 3 4 4 7% 64%	1673
	11th to 20th	Day	6% 4 2 3 3 2 3 3 3 6% 66%	1710
	21st to end	Day	6% 7% 2 4 3 2 3 3 4 6% 61%	1710
December	1st to 10th	Day	4 6% 2 5% 4 2 3 4 5% 7% 57%	1620
	11th to 20th	Day	5% 6% 2 4 4 3 3 4 5% 8% 55%	1926
	21st to end	Day	12% 9% 3 5% 5% 2 3 4 4 6% 47%	2794
January	1st to 10th	Night	4 6% 3 4 4 3 4 4 4 6% 59%	2647
	11th to 20th	Night	4 6% 3 4 5% 2 4 4 5% 7% 57%	2541
	21st to end	Night	4 7% 2 5% 5% 3 4 4 5% 6% 54%	2732
February	1st to 10th	Night	7% 8% 3 8% 4 3 4 4 4 6% 49%	2182
	11th to 20th	Night	4 7% 3 6% 7% 3 4 4 5% 7% 49%	2098
	21st to end	Night	5% 7% 3 6% 5% 3 4 4 5% 7% 52%	1776
March	1st to 10th	Night	5% 7% 3 4 4 2 4 5% 5% 6% 54%	2160
	11th to 20th	Night	9% 8% 3 4 4 2 3 3 4 6% 54%	2098
	21st to end	Night	10% 8% 3 4 4 2 4 6% 4 9% 46%	2023
April	1st to 10th	Night	10% 7% 3 4 4 2 4 4 5% 8% 50%	1800
	11th to 20th	Night	13% 5% 2 4 5% 3 4 4 5% 7% 47%	1777
	21st to end	Night	14% 6% 2 4 4 3 4 5% 5% 8% 45%	1696
May	1st to 10th	Night	11% 6% 3 6% 5% 2 6% 5% 6% 9% 43%	1620
	11th to 20th	Night	14% 6% 2 4 4 3 3 5% 6% 7% 47%	1593
	21st to end	Night	13% 5% 2 5% 4 2 4 6% 7% 9% 42%	1582
June	1st to 10th	Night	6% 3 1 3 5% 3 5% 6% 6% 11% 50%	1440
	11th to 20th	Night	7% 3 2 3 5% 3 4 5% 6% 8% 54%	1440
	21st to end	Night	3 3 2 4 5% 4 7% 7% 8% 9% 49%	1440
July	1st to 10th	Night	6% 4 2 5% 5% 4 5% 5% 7% 10% 46%	1440
	11th to 20th	Night	4 3 2 4 5% 2 6% 5% 5% 11% 52%	1440
	21st to end	Night	5% 3 2 5% 5% 3 6% 6% 7% 10% 50%	1576
August	1st to 10th	Night	4 3 2 4 5% 4 6% 7% 9% 11% 45%	1597
	11th to 20th	Night	4 4 2 4 4 3 5% 5% 7% 9% 53%	1765
	21st to end	Night	4 4 1 3 3 2 3 4 6% 7% 61%	1980
September	1st to 10th	Night	6% 3 2 4 4 3 4 5% 5% 8% 57%	1800
	11th to 20th	Night	7% 3 1 3 2 2 3 4 5% 7% 61%	1944
	21st to end	Night	7% 3 1 3 3 3 3 3 4 6% 63%	1980
October	1st to 10th	Night	11% 4 2 3 3 2 4 4 5% 7% 55%	1980
	11th to 20th	Night	8% 5% 1 2 2 2 3 2 3 6% 66%	2129
	21st to end	Night	7% 5% 2 3 3 2 2 4 3 6% 63%	2574
November	1st to 10th	Night	3 3 1 3 3 2 4 4 4 7% 65%	2405
	11th to 20th	Night	5% 4 2 3 4 2 4 3 5% 7% 61%	2470
	21st to end	Night	5% 5% 2 4 4 2 4 3 4 6% 60%	2470
December	1st to 10th	Night	5% 6% 2 6% 4 2 3 4 4 7% 57%	2555
	11th to 20th	Night	4 5% 2 3 4 2 3 5% 5% 9% 57%	3271
	21st to end	Night	10% 10% 3 5% 4 2 4 4 5% 7% 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	24% 5% 13% 32% 22% 4	1519
	11th to 20th	Day	28% 4 11% 31% 20% 5%	1448
	21st to end	Day	29% 4 13% 33% 17% 4	1639
February	1st to 10th	Day	35% 5% 12% 25% 17% 6%	1775
	11th to 20th	Day	33% 5% 10% 25% 22% 5%	1759
	21st to end	Day	29% 4 10% 24% 23% 9%	1480
March	1st to 10th	Day	26% 4 11% 27% 24% 8%	1800
	11th to 20th	Day	30% 5% 12% 22% 25% 7%	1862
	21st to end	Day	35% 7% 14% 25% 15% 4	2330
April	1st to 10th	Day	28% 5% 13% 25% 22% 6%	2160
	11th to 20th	Day	33% 5% 15% 23% 18% 6%	2134
	21st to end	Day	33% 6% 12% 28% 18% 3	2263
May	1st to 10th	Day	35% 7% 14% 27% 15% 2	2340
	11th to 20th	Day	33% 8% 20% 25% 13% 1	2306
	21st to end	Day	30% 8% 17% 27% 11% 6%	2690
June	1st to 10th	Day	20% 8% 18% 33% 16% 5%	2520
	11th to 20th	Day	24% 7% 12% 25% 23% 10%	2520
	21st to end	Day	19% 7% 11% 26% 27% 9%	2520
July	1st to 10th	Day	25% 7% 12% 26% 22% 8%	2451
	11th to 20th	Day	17% 6% 14% 28% 26% 9%	2445
	21st to end	Day	23% 9% 16% 30% 18% 4	2590
August	1st to 10th	Day	25% 9% 17% 29% 13% 6%	2327
	11th to 20th	Day	23% 6% 12% 25% 27% 7%	2133
	21st to end	Day	21% 5% 10% 27% 26% 12%	2376
September	1st to 10th	Day	22% 4 8% 26% 25% 15%	2160
	11th to 20th	Day	21% 5% 7% 23% 31% 12%	2016
	21st to end	Day	22% 3 6% 24% 34% 10%	1980
October	1st to 10th	Day	27% 4 9% 23% 28% 8%	1980
	11th to 20th	Day	21% 4 8% 24% 27% 15%	1810
	21st to end	Day	25% 3 10% 24% 27% 11%	1782
November	1st to 10th	Day	20% 4 13% 26% 26% 10%	1673
	11th to 20th	Day	22% 3 8% 29% 29% 9%	1710
	21st to end	Day	26% 2 9% 25% 29% 9%	1710
December	1st to 10th	Day	27% 4 11% 29% 25% 4	1620
	11th to 20th	Day	27% 4 9% 29% 28% 3	1924
	21st to end	Day	39% 4 10% 28% 15% 4	2794
January	1st to 10th	Night	26% 5% 12% 28% 26% 3	2647
	11th to 20th	Night	28% 5% 11% 26% 25% 6%	2541
	21st to end	Night	30% 4 11% 34% 17% 4	2732
February	1st to 10th	Night	37% 4 12% 22% 18% 6%	2182
	11th to 20th	Night	33% 6% 12% 28% 18% 3	2098
	21st to end	Night	32% 4 9% 25% 23% 7%	1776
March	1st to 10th	Night	29% 4 11% 24% 22% 10%	2160
	11th to 20th	Night	33% 4 11% 20% 26% 7%	2098
	21st to end	Night	36% 6% 14% 25% 16% 3	2023
April	1st to 10th	Night	33% 6% 11% 24% 19% 6%	1800
	11th to 20th	Night	36% 5% 14% 23% 18% 3	1777
	21st to end	Night	36% 6% 12% 24% 19% 2	1696
May	1st to 10th	Night	37% 8% 14% 26% 13% 2	1620
	11th to 20th	Night	35% 8% 20% 24% 11% 2	1594
	21st to end	Night	36% 12% 18% 21% 7% 6%	1583
June	1st to 10th	Night	26% 10% 23% 24% 13% 4	1440
	11th to 20th	Night	28% 7% 14% 23% 20% 9%	1440
	21st to end	Night	27% 10% 13% 23% 20% 7%	1440
July	1st to 10th	Night	33% 7% 14% 24% 18% 4	1400
	11th to 20th	Night	25% 8% 13% 26% 21% 6%	1392
	21st to end	Night	26% 10% 17% 29% 15% 3	1488
August	1st to 10th	Night	28% 12% 19% 25% 11% 4	1588
	11th to 20th	Night	26% 7% 15% 28% 18% 6%	1765
	21st to end	Night	21% 6% 13% 27% 23% 10%	1980
September	1st to 10th	Night	25% 6% 10% 22% 23% 13%	1800
	11th to 20th	Night	22% 7% 10% 23% 25% 13%	1944
	21st to end	Night	22% 5% 8% 24% 31% 10%	1980
October	1st to 10th	Night	28% 6% 11% 20% 27% 8%	1980
	11th to 20th	Night	21% 2 10% 25% 26% 15%	2129
	21st to end	Night	25% 4 11% 21% 26% 13%	2574
November	1st to 10th	Night	20% 4 9% 27% 28% 12%	2405
	11th to 20th	Night	23% 4 10% 26% 27% 9%	2470
	21st to end	Night	26% 3 9% 24% 27% 10%	2470
December	1st to 10th	Night	28% 4 11% 29% 21% 6%	2555
	11th to 20th	Night	25% 4 10% 30% 27% 4	3272
	21st to end	Night	35% 5% 12% 30% 17% 2	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	8% 7% 34% 33% 15% 2	270
	11th to 20th	Day	14% 7% 37% 32% 8% 2	243
	21st to end	Day	8% 8% 52% 27% 5% 1	264
February	1st to 10th	Day	11% 10% 48% 27% 3 2	240
	11th to 20th	Day	9% 10% 42% 27% 10% 3	240
	21st to end	Day	9% 13% 41% 28% 9% 1	198
March	1st to 10th	Day	10% 8% 35% 28% 16% 3	240
	11th to 20th	Day	14% 8% 33% 27% 17% 2	240
	21st to end	Day	13% 12% 35% 28% 10% 1	416
April	1st to 10th	Day	12% 15% 35% 25% 10% 3	420
	11th to 20th	Day	17% 13% 33% 25% 11% 1	412
	21st to end	Day	15% 12% 32% 26% 12% 2	523
May	1st to 10th	Day	15% 9% 27% 33% 14% 3	603
	11th to 20th	Day	17% 5% 27% 30% 17% 4	625
	21st to end	Day	13% 8% 27% 29% 18% 4	679
June	1st to 10th	Day	7% 5% 20% 30% 27% 10%	630
	11th to 20th	Day	7% 5% 27% 37% 21% 2	630
	21st to end	Day	7% 3 22% 38% 24% 6%	630
July	1st to 10th	Day	8% 2 18% 37% 28% 7%	621
	11th to 20th	Day	3 1 16% 38% 33% 9%	618
	21st to end	Day	6% 2 13% 36% 34% 9%	684
August	1st to 10th	Day	8% 2 12% 37% 33% 8%	626
	11th to 20th	Day	5% 2 21% 41% 23% 8%	447
	21st to end	Day	4 2 17% 41% 28% 8%	495
September	1st to 10th	Day	6% 4 20% 36% 25% 10%	450
	11th to 20th	Day	4 3 14% 37% 27% 14%	306
	21st to end	Day	14% 3 16% 31% 27% 9%	270
October	1st to 10th	Day	16% 3 19% 27% 23% 12%	270
	11th to 20th	Day	7% 8% 33% 27% 20% 5%	270
	21st to end	Day	14% 7% 33% 25% 16% 5%	297
November	1st to 10th	Day	5% 7% 34% 32% 17% 5%	270
	11th to 20th	Day	9% 6% 32% 34% 16% 3	270
	21st to end	Day	12% 7% 28% 38% 12% 3	270
December	1st to 10th	Day	6% 10% 36% 36% 10% 2	270
	11th to 20th	Day	13% 10% 33% 29% 15%	270
	21st to end	Day	16% 9% 37% 27% 8% 2	297
January	1st to 10th	Night	7% 9% 36% 34% 13% 1	950
	11th to 20th	Night	8% 9% 35% 38% 8% 1	908
	21st to end	Night	8% 8% 43% 35% 7%	950
February	1st to 10th	Night	10% 9% 42% 34% 4	720
	11th to 20th	Night	7% 8% 45% 34% 6% 1	704
	21st to end	Night	8% 9% 43% 36% 4	592
March	1st to 10th	Night	9% 9% 38% 38% 7%	720
	11th to 20th	Night	14% 6% 39% 33% 7% 1	658
	21st to end	Night	14% 9% 34% 36% 6%	594
April	1st to 10th	Night	14% 10% 40% 33% 4	540
	11th to 20th	Night	16% 7% 44% 30% 3	533
	21st to end	Night	18% 9% 31% 34% 7% 1	540
May	1st to 10th	Night	14% 6% 32% 39% 9%	540
	11th to 20th	Night	17% 5% 28% 37% 11% 1	531
	21st to end	Night	14% 6% 35% 32% 12%	584
June	1st to 10th	Night	8% 6% 29% 40% 16% 1	540
	11th to 20th	Night	9% 5% 39% 39% 9%	540
	21st to end	Night	4 4 27% 50% 15%	540
July	1st to 10th	Night	8% 3 23% 52% 14%	525
	11th to 20th	Night	5% 2 19% 56% 18% 1	522
	21st to end	Night	5% 1 18% 51% 23% 1	591
August	1st to 10th	Night	7% 2 16% 52% 22% 1	537
	11th to 20th	Night	5% 3 23% 54% 15%	534
	21st to end	Night	5% 2 22% 53% 17% 1	594
September	1st to 10th	Night	7% 2 26% 51% 13% 1	540
	11th to 20th	Night	9% 3 28% 44% 15% 1	540
	21st to end	Night	9% 4 28% 44% 15%	540
October	1st to 10th	Night	13% 9% 24% 38% 15% 1	540
	11th to 20th	Night	11% 6% 29% 38% 14% 1	689
	21st to end	Night	10% 7% 31% 37% 14% 1	990
November	1st to 10th	Night	5% 5% 31% 46% 12% 1	925
	11th to 20th	Night	8% 6% 36% 39% 10%	950
	21st to end	Night	8% 5% 34% 39% 12% 1	950
December	1st to 10th	Night	8% 7% 42% 37% 7%	950
	11th to 20th	Night	7% 8% 36% 40% 8% 1	950
	21st to end	Night	11% 9% 38% 36% 5%	1045

Page generated at 2024-01-09 05:14:43. Version ac07

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