Wainwright
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Wainwright clear sky chart from 2005-11-06 to 2024-02-05.

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	10% 9% 4 8% 7% 4 6% 6% 6% 8% 34%	77582
	Night	7% 9% 4 8% 8% 4 6% 6% 6% 8% 34%	81230
Transparency	Day	47% 8% 16% 22% 7% 1	77284
	Night	47% 8% 15% 21% 9% 1	81108
Seeing	Day	13% 7% 27% 30% 17% 5%	14453
	Night	12% 6% 28% 35% 16% 2	23779

By Month

Percentage Cloud Cover NW (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% 10% 6% 13% 12% 6% 5% 4 6% 7% 26%	2219
	11th to 20th	Day	5% 8% 3 9% 9% 6% 8% 12% 10% 6% 23%	2199
	21st to end	Day	6% 14% 6% 9% 9% 4 6% 5% 5% 7% 30%	2484
February	1st to 10th	Day	8% 11% 6% 12% 9% 6% 6% 6% 5% 7% 24%	1535
	11th to 20th	Day	7% 13% 6% 11% 9% 4 5% 6% 7% 8% 24%	1575
	21st to end	Day	5% 12% 5% 10% 10% 4 8% 7% 8% 9% 20%	1332
March	1st to 10th	Day	8% 13% 5% 11% 10% 6% 6% 7% 6% 7% 21%	1821
	11th to 20th	Day	9% 11% 4 8% 7% 4 5% 5% 5% 8% 34%	1979
	21st to end	Day	10% 11% 5% 11% 9% 4 6% 4 6% 7% 26%	2178
April	1st to 10th	Day	8% 10% 5% 10% 8% 4 5% 7% 5% 7% 31%	2239
	11th to 20th	Day	12% 11% 5% 9% 6% 3 5% 5% 7% 7% 30%	2310
	21st to end	Day	13% 11% 4 6% 6% 3 5% 5% 6% 9% 31%	2377
May	1st to 10th	Day	11% 9% 4 8% 7% 4 7% 5% 6% 8% 30%	2533
	11th to 20th	Day	9% 7% 3 6% 7% 4 6% 6% 6% 9% 38%	2654
	21st to end	Day	16% 7% 3 6% 6% 4 6% 7% 6% 7% 33%	2917
June	1st to 10th	Day	15% 7% 3 6% 7% 5% 5% 6% 7% 7% 32%	2700
	11th to 20th	Day	19% 8% 4 8% 7% 3 6% 6% 7% 8% 24%	2700
	21st to end	Day	11% 6% 2 5% 6% 4 6% 7% 7% 10% 36%	2700
July	1st to 10th	Day	9% 4 3 5% 5% 3 6% 6% 8% 10% 41%	2700
	11th to 20th	Day	11% 6% 2 5% 6% 5% 6% 6% 7% 10% 37%	2700
	21st to end	Day	7% 5% 2 4 5% 3 6% 6% 7% 9% 47%	2938
August	1st to 10th	Day	9% 5% 3 6% 6% 3 7% 6% 7% 8% 39%	2629
	11th to 20th	Day	10% 6% 2 5% 5% 3 4 6% 6% 9% 44%	2299
	21st to end	Day	9% 6% 3 5% 5% 2 4 5% 7% 9% 45%	2574
September	1st to 10th	Day	10% 6% 2 5% 7% 4 5% 4 6% 8% 42%	2245
	11th to 20th	Day	15% 8% 3 6% 5% 3 4 4 5% 6% 42%	2044
	21st to end	Day	10% 6% 3 5% 4 3 4 4 6% 8% 48%	1976
October	1st to 10th	Day	12% 10% 4 6% 6% 3 4 5% 5% 7% 39%	1800
	11th to 20th	Day	11% 9% 5% 5% 5% 3 4 5% 5% 7% 40%	1764
	21st to end	Day	7% 11% 4 10% 8% 4 5% 6% 6% 7% 32%	1683
November	1st to 10th	Day	12% 13% 5% 9% 8% 4 6% 5% 6% 7% 26%	1488
	11th to 20th	Day	7% 13% 6% 12% 9% 3 4 6% 6% 7% 27%	1506
	21st to end	Day	6% 11% 6% 10% 8% 4 6% 5% 6% 8% 29%	1330
December	1st to 10th	Day	7% 11% 7% 10% 8% 5% 8% 7% 7% 7% 22%	1330
	11th to 20th	Day	7% 9% 5% 11% 10% 5% 9% 6% 6% 8% 25%	1682
	21st to end	Day	4 8% 3 8% 7% 5% 5% 4 5% 8% 43%	2442
January	1st to 10th	Night	4 10% 5% 12% 10% 6% 7% 7% 7% 8% 23%	4726
	11th to 20th	Night	3 7% 4 9% 10% 6% 7% 11% 8% 8% 26%	4699
	21st to end	Night	6% 12% 5% 10% 7% 4 5% 5% 6% 8% 32%	5200
February	1st to 10th	Night	5% 10% 5% 12% 9% 5% 7% 7% 7% 8% 25%	2518
	11th to 20th	Night	7% 10% 5% 8% 10% 5% 6% 7% 7% 8% 27%	2272
	21st to end	Night	5% 8% 5% 10% 9% 5% 6% 7% 6% 9% 30%	1924
March	1st to 10th	Night	7% 10% 5% 11% 9% 4 6% 6% 6% 8% 27%	2138
	11th to 20th	Night	6% 10% 5% 9% 8% 4 5% 6% 6% 8% 33%	1980
	21st to end	Night	8% 11% 5% 8% 8% 4 6% 6% 7% 8% 28%	2178
April	1st to 10th	Night	6% 10% 3 6% 6% 3 6% 6% 6% 9% 39%	1717
	11th to 20th	Night	8% 11% 4 8% 8% 4 6% 5% 7% 8% 29%	1601
	21st to end	Night	13% 10% 4 7% 5% 3 4 4 5% 8% 35%	1582
May	1st to 10th	Night	11% 8% 3 7% 8% 3 7% 6% 6% 7% 34%	1423
	11th to 20th	Night	9% 6% 3 5% 6% 3 5% 6% 7% 10% 40%	1239
	21st to end	Night	18% 5% 3 7% 6% 4 5% 6% 6% 8% 32%	1358
June	1st to 10th	Night	13% 7% 4 7% 7% 4 6% 6% 6% 8% 32%	1260
	11th to 20th	Night	17% 8% 4 7% 7% 4 6% 6% 5% 8% 26%	1260
	21st to end	Night	7% 5% 3 5% 7% 4 6% 7% 8% 9% 40%	1260
July	1st to 10th	Night	9% 6% 2 4 6% 3 4 4 6% 10% 46%	1260
	11th to 20th	Night	9% 5% 2 5% 5% 3 4 5% 9% 9% 43%	1260
	21st to end	Night	7% 3 2 3 4 2 5% 6% 5% 9% 52%	1379
August	1st to 10th	Night	7% 4 2 5% 7% 4 6% 6% 7% 9% 42%	1307
	11th to 20th	Night	10% 6% 3 5% 5% 3 6% 4 6% 11% 42%	1602
	21st to end	Night	8% 5% 2 6% 4 3 5% 4 5% 9% 48%	1782
September	1st to 10th	Night	9% 5% 2 6% 5% 4 4 6% 5% 8% 46%	1714
	11th to 20th	Night	11% 6% 3 5% 4 2 4 4 5% 7% 49%	1913
	21st to end	Night	7% 7% 2 5% 4 3 5% 4 5% 8% 48%	1984
October	1st to 10th	Night	10% 8% 3 6% 6% 4 6% 5% 7% 7% 39%	2160
	11th to 20th	Night	8% 8% 4 7% 7% 3 4 5% 6% 8% 40%	2196
	21st to end	Night	8% 11% 4 8% 6% 4 5% 6% 6% 8% 34%	2654
November	1st to 10th	Night	12% 14% 5% 8% 7% 4 5% 5% 6% 6% 29%	2590
	11th to 20th	Night	8% 10% 4 12% 11% 6% 6% 6% 5% 7% 26%	2670
	21st to end	Night	5% 10% 6% 11% 8% 4 5% 5% 6% 8% 31%	2850
December	1st to 10th	Night	6% 12% 6% 11% 10% 5% 7% 5% 6% 7% 26%	2850
	11th to 20th	Night	6% 12% 5% 13% 11% 6% 6% 6% 6% 7% 22%	3510
	21st to end	Night	3 7% 4 8% 7% 4 6% 5% 6% 7% 45%	5214

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	58% 6% 13% 18% 5%	2219
	11th to 20th	Day	52% 9% 13% 15% 10% 1	2220
	21st to end	Day	53% 7% 15% 20% 6%	2484
February	1st to 10th	Day	59% 6% 11% 18% 6%	1535
	11th to 20th	Day	55% 7% 13% 17% 8%	1584
	21st to end	Day	56% 7% 12% 18% 7%	1332
March	1st to 10th	Day	60% 8% 13% 14% 4	1821
	11th to 20th	Day	48% 7% 15% 20% 9% 1	1980
	21st to end	Day	56% 8% 15% 17% 4	2178
April	1st to 10th	Day	51% 7% 13% 20% 8% 1	2239
	11th to 20th	Day	52% 6% 13% 20% 9% 1	2310
	21st to end	Day	47% 8% 14% 20% 10% 1	2377
May	1st to 10th	Day	50% 7% 12% 21% 10%	2533
	11th to 20th	Day	41% 7% 12% 28% 11% 1	2658
	21st to end	Day	47% 9% 13% 20% 11%	2918
June	1st to 10th	Day	48% 8% 14% 21% 8%	2700
	11th to 20th	Day	55% 11% 14% 15% 4 1	2700
	21st to end	Day	41% 11% 20% 21% 7% 1	2700
July	1st to 10th	Day	34% 11% 22% 26% 6% 1	2626
	11th to 20th	Day	40% 11% 22% 24% 3	2619
	21st to end	Day	31% 10% 22% 31% 6%	2775
August	1st to 10th	Day	38% 11% 22% 25% 4	2611
	11th to 20th	Day	34% 10% 23% 25% 8%	2299
	21st to end	Day	33% 9% 19% 31% 7% 1	2574
September	1st to 10th	Day	39% 7% 17% 25% 9% 3	2245
	11th to 20th	Day	44% 5% 16% 27% 8%	2044
	21st to end	Day	34% 8% 16% 29% 10% 2	1976
October	1st to 10th	Day	45% 7% 16% 24% 8%	1800
	11th to 20th	Day	42% 7% 16% 25% 9%	1764
	21st to end	Day	50% 7% 14% 21% 8% 1	1683
November	1st to 10th	Day	58% 5% 13% 18% 5% 1	1488
	11th to 20th	Day	55% 7% 16% 18% 4	1506
	21st to end	Day	52% 8% 17% 19% 5%	1330
December	1st to 10th	Day	57% 7% 13% 15% 6% 1	1330
	11th to 20th	Day	55% 8% 15% 17% 5%	1684
	21st to end	Day	41% 5% 11% 28% 15% 2	2442
January	1st to 10th	Night	55% 9% 14% 16% 6%	4726
	11th to 20th	Night	51% 6% 15% 17% 10% 1	4740
	21st to end	Night	50% 7% 14% 23% 6%	5200
February	1st to 10th	Night	53% 8% 13% 18% 8% 1	2518
	11th to 20th	Night	51% 9% 14% 17% 10%	2273
	21st to end	Night	48% 8% 12% 22% 9% 1	1924
March	1st to 10th	Night	53% 7% 15% 17% 7% 1	2138
	11th to 20th	Night	48% 6% 12% 24% 9% 1	1980
	21st to end	Night	51% 8% 15% 18% 8%	2178
April	1st to 10th	Night	41% 8% 15% 21% 15% 1	1717
	11th to 20th	Night	51% 8% 11% 18% 11% 1	1601
	21st to end	Night	47% 6% 11% 22% 13% 2	1582
May	1st to 10th	Night	46% 6% 10% 24% 12% 1	1423
	11th to 20th	Night	38% 9% 10% 27% 15% 1	1239
	21st to end	Night	47% 9% 11% 23% 9% 2	1358
June	1st to 10th	Night	47% 8% 13% 23% 8% 1	1260
	11th to 20th	Night	54% 10% 12% 16% 8%	1260
	21st to end	Night	37% 10% 20% 25% 7% 1	1260
July	1st to 10th	Night	32% 9% 20% 30% 8% 1	1225
	11th to 20th	Night	34% 11% 24% 23% 7% 1	1218
	21st to end	Night	26% 9% 23% 32% 9%	1302
August	1st to 10th	Night	35% 11% 22% 26% 6%	1300
	11th to 20th	Night	35% 9% 20% 27% 8% 1	1602
	21st to end	Night	33% 6% 14% 34% 13% 1	1782
September	1st to 10th	Night	35% 8% 19% 23% 10% 5%	1714
	11th to 20th	Night	35% 6% 15% 31% 10% 2	1913
	21st to end	Night	33% 7% 15% 30% 14% 2	1984
October	1st to 10th	Night	41% 9% 14% 26% 10% 1	2160
	11th to 20th	Night	40% 6% 15% 29% 10%	2196
	21st to end	Night	47% 8% 14% 24% 7% 1	2654
November	1st to 10th	Night	55% 6% 13% 17% 8% 1	2590
	11th to 20th	Night	57% 7% 14% 16% 6% 1	2670
	21st to end	Night	50% 8% 19% 18% 5%	2850
December	1st to 10th	Night	57% 6% 11% 17% 8% 2	2850
	11th to 20th	Night	59% 9% 14% 11% 6%	3507
	21st to end	Night	38% 6% 15% 21% 18% 3	5214

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	9% 5% 33% 31% 17% 6%	180
	11th to 20th	Day	12% 6% 29% 27% 22% 4	180
	21st to end	Day	13% 9% 33% 30% 13% 3	198
February	1st to 10th	Day	12% 9% 34% 32% 11% 3	196
	11th to 20th	Day	12% 6% 35% 31% 13% 3	240
	21st to end	Day	10% 6% 29% 27% 22% 6%	198
March	1st to 10th	Day	12% 8% 32% 33% 13% 2	378
	11th to 20th	Day	11% 8% 34% 27% 15% 4	420
	21st to end	Day	15% 5% 29% 32% 16% 4	462
April	1st to 10th	Day	11% 11% 39% 27% 9% 3	420
	11th to 20th	Day	15% 8% 28% 33% 13% 3	412
	21st to end	Day	18% 11% 30% 29% 11% 2	457
May	1st to 10th	Day	14% 8% 26% 31% 17% 5%	603
	11th to 20th	Day	11% 7% 23% 33% 20% 6%	625
	21st to end	Day	18% 6% 22% 28% 19% 8%	679
June	1st to 10th	Day	15% 9% 25% 34% 14% 3	630
	11th to 20th	Day	19% 9% 25% 27% 14% 6%	630
	21st to end	Day	11% 7% 23% 28% 22% 10%	630
July	1st to 10th	Day	10% 4 19% 32% 26% 9%	621
	11th to 20th	Day	13% 5% 25% 29% 20% 7%	618
	21st to end	Day	8% 4 21% 30% 29% 8%	684
August	1st to 10th	Day	11% 5% 19% 30% 27% 9%	605
	11th to 20th	Day	10% 5% 24% 32% 22% 8%	437
	21st to end	Day	10% 6% 21% 31% 22% 8%	495
September	1st to 10th	Day	14% 7% 34% 28% 14% 4	450
	11th to 20th	Day	21% 8% 23% 28% 16% 5%	450
	21st to end	Day	13% 13% 27% 30% 14% 3	446
October	1st to 10th	Day	15% 9% 24% 34% 14% 4	270
	11th to 20th	Day	16% 8% 33% 28% 14% 2	270
	21st to end	Day	11% 11% 37% 27% 11% 3	297
November	1st to 10th	Day	19% 7% 26% 33% 11% 3	270
	11th to 20th	Day	13% 8% 38% 29% 11% 1	264
	21st to end	Day	9% 8% 33% 35% 10% 5%	180
December	1st to 10th	Day	12% 5% 33% 28% 17% 6%	180
	11th to 20th	Day	9% 13% 30% 28% 18% 1	180
	21st to end	Day	11% 4 28% 31% 21% 6%	198
January	1st to 10th	Night	11% 7% 31% 37% 13% 2	950
	11th to 20th	Night	10% 7% 33% 34% 14% 1	950
	21st to end	Night	13% 10% 34% 31% 10% 1	1031
February	1st to 10th	Night	9% 8% 26% 38% 17% 3	738
	11th to 20th	Night	12% 7% 32% 32% 16% 2	704
	21st to end	Night	9% 3 22% 41% 21% 4	592
March	1st to 10th	Night	10% 5% 28% 39% 16% 2	720
	11th to 20th	Night	11% 5% 30% 37% 15% 3	720
	21st to end	Night	14% 5% 28% 35% 16% 3	792
April	1st to 10th	Night	11% 7% 29% 34% 17% 2	555
	11th to 20th	Night	14% 6% 29% 37% 12% 2	533
	21st to end	Night	17% 8% 24% 38% 13%	540
May	1st to 10th	Night	15% 5% 25% 36% 17% 3	523
	11th to 20th	Night	12% 6% 21% 41% 18% 2	354
	21st to end	Night	19% 5% 24% 29% 22% 2	389
June	1st to 10th	Night	17% 7% 24% 34% 16% 3	360
	11th to 20th	Night	21% 7% 21% 28% 22% 2	360
	21st to end	Night	9% 2 23% 36% 26% 4	360
July	1st to 10th	Night	10% 7% 17% 41% 25%	350
	11th to 20th	Night	11% 4 21% 41% 20% 3	348
	21st to end	Night	6% 5% 19% 40% 26% 4	394
August	1st to 10th	Night	9% 4 18% 37% 27% 6%	393
	11th to 20th	Night	14% 3 18% 40% 25% 2	534
	21st to end	Night	9% 3 23% 39% 25% 1	594
September	1st to 10th	Night	12% 3 23% 40% 19% 2	540
	11th to 20th	Night	13% 4 21% 44% 17% 1	653
	21st to end	Night	10% 5% 31% 36% 18% 1	720
October	1st to 10th	Night	13% 4 29% 36% 16% 1	720
	11th to 20th	Night	12% 4 31% 35% 15% 2	720
	21st to end	Night	14% 6% 32% 36% 11%	872
November	1st to 10th	Night	19% 6% 32% 30% 11% 2	925
	11th to 20th	Night	15% 7% 32% 33% 10% 3	950
	21st to end	Night	10% 6% 36% 36% 11% 1	950
December	1st to 10th	Night	13% 7% 31% 29% 17% 4	950
	11th to 20th	Night	12% 8% 36% 30% 13% 1	950
	21st to end	Night	9% 4 32% 34% 18% 3	1045

Page generated at 2024-02-02 03:20:32. Version ac07

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