Whiteway
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Whiteway clear sky chart from 2005-11-06 to 2024-01-14.

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	22% 15% 6% 9% 6% 3 4 4 4 6% 21%	74612
	Night	23% 17% 6% 9% 6% 3 4 4 4 5% 19%	75147
Transparency	Day	65% 6% 10% 13% 5%	74303
	Night	67% 6% 10% 12% 5%	74991
Seeing	Day	33% 19% 27% 15% 5% 1	16955
	Night	32% 18% 29% 17% 4	23691

By Month

Percentage Cloud Cover NE (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	20% 22% 9% 13% 6% 3 3 3 4 4 11%	1326
	11th to 20th	Day	22% 19% 6% 11% 8% 3 5% 4 3 4 14%	1447
	21st to end	Day	21% 18% 9% 14% 7% 3 5% 2 3 5% 13%	1584
February	1st to 10th	Day	21% 13% 8% 11% 10% 5% 5% 4 4 5% 14%	1550
	11th to 20th	Day	21% 18% 7% 12% 8% 3 5% 4 4 5% 14%	1591
	21st to end	Day	14% 17% 9% 16% 8% 4 4 4 4 5% 16%	1480
March	1st to 10th	Day	18% 16% 9% 13% 9% 4 4 4 4 4 15%	1802
	11th to 20th	Day	17% 15% 8% 12% 7% 4 5% 4 4 5% 19%	1980
	21st to end	Day	24% 20% 8% 11% 7% 2 3 3 3 3 16%	2178
April	1st to 10th	Day	19% 17% 6% 11% 8% 3 5% 3 4 4 19%	2176
	11th to 20th	Day	23% 18% 5% 9% 6% 3 3 3 4 4 22%	2311
	21st to end	Day	22% 19% 5% 7% 6% 3 4 4 4 5% 21%	2340
May	1st to 10th	Day	22% 18% 6% 8% 5% 3 4 4 5% 6% 20%	2340
	11th to 20th	Day	23% 15% 4 8% 6% 3 4 3 4 6% 24%	2501
	21st to end	Day	21% 12% 6% 8% 6% 4 5% 4 6% 7% 22%	2918
June	1st to 10th	Day	28% 15% 5% 9% 7% 3 4 3 4 5% 17%	2700
	11th to 20th	Day	26% 13% 4 6% 6% 4 5% 3 4 6% 23%	2700
	21st to end	Day	25% 13% 4 6% 6% 3 4 3 5% 6% 23%	2700
July	1st to 10th	Day	21% 11% 4 8% 5% 3 5% 4 5% 7% 27%	2700
	11th to 20th	Day	19% 12% 5% 8% 7% 4 4 5% 5% 6% 25%	2680
	21st to end	Day	22% 10% 4 8% 7% 3 6% 5% 5% 6% 23%	2745
August	1st to 10th	Day	23% 10% 3 7% 6% 3 5% 5% 5% 8% 24%	2391
	11th to 20th	Day	21% 11% 4 8% 7% 4 4 4 5% 6% 24%	2305
	21st to end	Day	20% 10% 4 7% 6% 4 5% 5% 5% 8% 26%	2574
September	1st to 10th	Day	18% 10% 4 7% 5% 4 5% 5% 6% 6% 31%	2152
	11th to 20th	Day	24% 8% 4 7% 5% 3 5% 4 4 6% 31%	1980
	21st to end	Day	19% 9% 3 5% 6% 3 4 5% 5% 7% 34%	1980
October	1st to 10th	Day	22% 12% 4 6% 5% 3 4 4 4 6% 30%	1895
	11th to 20th	Day	24% 15% 5% 7% 6% 4 5% 5% 4 5% 21%	1746
	21st to end	Day	24% 18% 4 8% 6% 4 4 4 5% 5% 19%	1782
November	1st to 10th	Day	21% 16% 5% 8% 6% 3 3 4 4 5% 25%	1649
	11th to 20th	Day	23% 18% 6% 8% 6% 3 3 4 4 7% 18%	1520
	21st to end	Day	24% 22% 7% 7% 6% 2 3 3 4 4 18%	1449
December	1st to 10th	Day	25% 18% 7% 10% 6% 2 4 4 3 5% 15%	1330
	11th to 20th	Day	15% 24% 10% 12% 6% 3 3 3 3 5% 15%	1668
	21st to end	Day	21% 24% 7% 10% 6% 3 4 3 4 4 14%	2442
January	1st to 10th	Night	20% 19% 10% 11% 8% 3 4 3 4 3 13%	2839
	11th to 20th	Night	22% 19% 8% 11% 7% 3 5% 4 3 5% 12%	2584
	21st to end	Night	20% 16% 9% 13% 8% 3 5% 3 3 5% 14%	2772
February	1st to 10th	Night	21% 16% 8% 13% 9% 4 4 3 4 5% 13%	2408
	11th to 20th	Night	23% 18% 7% 12% 7% 3 4 4 3 5% 14%	2255
	21st to end	Night	15% 18% 8% 14% 7% 5% 4 4 4 5% 16%	1776
March	1st to 10th	Night	17% 16% 10% 12% 7% 4 5% 4 4 4 18%	2145
	11th to 20th	Night	14% 15% 8% 11% 9% 3 5% 4 5% 5% 20%	1979
	21st to end	Night	25% 22% 7% 11% 6% 2 3 3 2 2 16%	2178
April	1st to 10th	Night	22% 19% 9% 9% 6% 2 4 3 3 4 20%	1779
	11th to 20th	Night	24% 17% 6% 8% 4 4 3 4 3 5% 23%	1598
	21st to end	Night	25% 22% 5% 7% 4 1 4 3 3 3 21%	1620
May	1st to 10th	Night	25% 18% 6% 7% 5% 4 4 4 4 5% 17%	1620
	11th to 20th	Night	26% 14% 3 7% 5% 3 4 4 5% 6% 23%	1389
	21st to end	Night	29% 13% 4 7% 6% 3 5% 3 5% 5% 20%	1356
June	1st to 10th	Night	29% 16% 5% 7% 5% 3 4 4 3 6% 18%	1260
	11th to 20th	Night	26% 13% 5% 7% 6% 3 5% 4 5% 6% 21%	1260
	21st to end	Night	29% 13% 5% 7% 5% 3 3 4 4 7% 20%	1260
July	1st to 10th	Night	25% 12% 4 8% 6% 3 6% 3 4 7% 21%	1260
	11th to 20th	Night	25% 14% 5% 7% 6% 3 5% 4 5% 5% 21%	1278
	21st to end	Night	25% 13% 5% 8% 5% 3 5% 4 5% 5% 21%	1573
August	1st to 10th	Night	23% 13% 4 7% 6% 3 4 5% 6% 7% 23%	1546
	11th to 20th	Night	24% 13% 6% 7% 6% 3 4 3 5% 5% 24%	1595
	21st to end	Night	22% 10% 4 8% 5% 4 4 5% 5% 7% 27%	1782
September	1st to 10th	Night	22% 11% 4 6% 5% 3 4 4 5% 7% 30%	1805
	11th to 20th	Night	25% 12% 3 7% 5% 3 4 4 4 6% 28%	1980
	21st to end	Night	21% 12% 4 7% 6% 3 4 4 4 6% 32%	1980
October	1st to 10th	Night	25% 13% 4 7% 5% 3 4 3 4 6% 27%	2065
	11th to 20th	Night	26% 14% 3 7% 5% 3 3 5% 5% 6% 23%	2209
	21st to end	Night	26% 18% 5% 7% 5% 3 5% 3 3 4 21%	2574
November	1st to 10th	Night	23% 19% 4 6% 6% 3 3 4 4 5% 23%	2427
	11th to 20th	Night	24% 18% 7% 7% 6% 3 4 4 4 5% 20%	2660
	21st to end	Night	19% 20% 6% 8% 5% 4 5% 4 4 5% 20%	2729
December	1st to 10th	Night	22% 19% 7% 11% 6% 3 4 3 3 4 16%	2850
	11th to 20th	Night	20% 23% 9% 12% 9% 3 4 2 3 3 11%	3531
	21st to end	Night	21% 21% 8% 10% 6% 3 4 4 3 4 18%	5225

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	78% 5% 7% 7% 3	1327
	11th to 20th	Day	73% 6% 8% 9% 4 1	1447
	21st to end	Day	76% 5% 4 9% 5% 1	1584
February	1st to 10th	Day	73% 5% 9% 7% 5% 1	1550
	11th to 20th	Day	74% 5% 9% 8% 3	1598
	21st to end	Day	70% 6% 9% 7% 6% 2	1480
March	1st to 10th	Day	73% 5% 7% 10% 4 1	1806
	11th to 20th	Day	70% 6% 8% 12% 4	1980
	21st to end	Day	75% 5% 7% 10% 2 2	2178
April	1st to 10th	Day	70% 5% 8% 12% 5%	2176
	11th to 20th	Day	68% 4 8% 11% 8% 1	2311
	21st to end	Day	68% 5% 8% 11% 7% 1	2340
May	1st to 10th	Day	65% 6% 11% 10% 7% 1	2340
	11th to 20th	Day	63% 6% 12% 13% 5% 1	2505
	21st to end	Day	63% 6% 10% 15% 6%	2918
June	1st to 10th	Day	72% 5% 8% 11% 4 1	2700
	11th to 20th	Day	64% 6% 12% 12% 6%	2700
	21st to end	Day	62% 7% 11% 14% 5%	2700
July	1st to 10th	Day	56% 9% 12% 18% 6%	2625
	11th to 20th	Day	60% 8% 13% 14% 6%	2598
	21st to end	Day	61% 9% 13% 13% 4	2592
August	1st to 10th	Day	59% 8% 13% 16% 5%	2377
	11th to 20th	Day	60% 7% 12% 15% 5%	2305
	21st to end	Day	57% 7% 15% 17% 4	2574
September	1st to 10th	Day	53% 8% 12% 19% 8%	2152
	11th to 20th	Day	55% 6% 11% 18% 9% 1	1980
	21st to end	Day	48% 8% 16% 20% 7% 1	1980
October	1st to 10th	Day	57% 6% 12% 17% 8% 1	1895
	11th to 20th	Day	66% 5% 10% 13% 5%	1746
	21st to end	Day	68% 7% 8% 13% 4 1	1782
November	1st to 10th	Day	63% 7% 13% 12% 5%	1649
	11th to 20th	Day	67% 7% 9% 12% 5%	1520
	21st to end	Day	70% 6% 11% 9% 4	1449
December	1st to 10th	Day	73% 5% 8% 10% 3	1330
	11th to 20th	Day	74% 6% 8% 8% 4	1667
	21st to end	Day	74% 7% 9% 9% 2	2442
January	1st to 10th	Night	75% 6% 7% 8% 4	2839
	11th to 20th	Night	74% 7% 7% 8% 4	2584
	21st to end	Night	72% 5% 8% 10% 4	2772
February	1st to 10th	Night	75% 4 8% 8% 4 1	2408
	11th to 20th	Night	73% 6% 8% 10% 3	2259
	21st to end	Night	68% 8% 8% 10% 6%	1776
March	1st to 10th	Night	68% 6% 8% 11% 6% 1	2154
	11th to 20th	Night	66% 6% 11% 12% 5% 1	1980
	21st to end	Night	75% 4 7% 9% 5% 1	2178
April	1st to 10th	Night	69% 5% 8% 11% 6% 1	1779
	11th to 20th	Night	66% 4 8% 13% 7% 1	1598
	21st to end	Night	69% 4 7% 12% 7%	1620
May	1st to 10th	Night	69% 6% 9% 10% 5%	1620
	11th to 20th	Night	61% 7% 9% 16% 5% 1	1390
	21st to end	Night	66% 7% 11% 12% 5%	1357
June	1st to 10th	Night	68% 5% 10% 11% 4	1260
	11th to 20th	Night	63% 8% 12% 13% 4	1260
	21st to end	Night	63% 6% 13% 13% 4	1260
July	1st to 10th	Night	62% 9% 11% 14% 4	1226
	11th to 20th	Night	65% 7% 11% 14% 4	1236
	21st to end	Night	64% 9% 8% 15% 3	1486
August	1st to 10th	Night	59% 8% 16% 13% 4	1535
	11th to 20th	Night	62% 7% 13% 13% 5%	1595
	21st to end	Night	55% 8% 15% 18% 4	1782
September	1st to 10th	Night	53% 8% 12% 19% 7% 1	1805
	11th to 20th	Night	57% 6% 13% 15% 8% 1	1980
	21st to end	Night	53% 6% 14% 19% 7%	1980
October	1st to 10th	Night	58% 6% 12% 17% 6% 1	2065
	11th to 20th	Night	62% 6% 13% 13% 5%	2209
	21st to end	Night	68% 6% 10% 11% 5% 1	2574
November	1st to 10th	Night	63% 7% 13% 12% 5%	2427
	11th to 20th	Night	66% 8% 11% 11% 3	2660
	21st to end	Night	65% 8% 12% 11% 4	2729
December	1st to 10th	Night	72% 7% 7% 11% 4	2850
	11th to 20th	Night	79% 4 6% 7% 3	3533
	21st to end	Night	68% 8% 9% 12% 2	5225

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	34% 26% 27% 11% 2	370
	11th to 20th	Day	33% 24% 28% 12% 2 1	349
	21st to end	Day	32% 26% 28% 11% 2	374
February	1st to 10th	Day	32% 25% 28% 13% 2	340
	11th to 20th	Day	34% 31% 24% 9% 2	336
	21st to end	Day	28% 30% 30% 10% 3	280
March	1st to 10th	Day	33% 29% 28% 8% 2	340
	11th to 20th	Day	30% 24% 26% 13% 4 2	340
	21st to end	Day	35% 22% 29% 9% 4 1	374
April	1st to 10th	Day	36% 24% 26% 11% 4	442
	11th to 20th	Day	37% 20% 25% 13% 3 1	589
	21st to end	Day	35% 22% 25% 15% 3	600
May	1st to 10th	Day	36% 21% 23% 13% 5% 1	603
	11th to 20th	Day	28% 18% 32% 16% 5% 2	624
	21st to end	Day	36% 17% 28% 15% 3 1	680
June	1st to 10th	Day	43% 13% 25% 14% 4 1	630
	11th to 20th	Day	35% 16% 27% 15% 5% 1	630
	21st to end	Day	31% 15% 31% 16% 5% 2	630
July	1st to 10th	Day	30% 15% 30% 16% 7% 1	620
	11th to 20th	Day	28% 14% 32% 21% 5% 1	618
	21st to end	Day	32% 15% 25% 20% 7%	685
August	1st to 10th	Day	31% 11% 29% 20% 7% 2	625
	11th to 20th	Day	27% 16% 27% 22% 7% 1	617
	21st to end	Day	29% 14% 26% 23% 8% 1	693
September	1st to 10th	Day	25% 13% 27% 26% 8% 1	478
	11th to 20th	Day	34% 19% 24% 18% 4 1	360
	21st to end	Day	26% 18% 34% 16% 6%	360
October	1st to 10th	Day	28% 19% 32% 16% 5%	360
	11th to 20th	Day	33% 20% 24% 16% 6% 1	360
	21st to end	Day	35% 23% 23% 13% 3 2	396
November	1st to 10th	Day	38% 20% 26% 12% 3 1	365
	11th to 20th	Day	37% 22% 21% 15% 4 1	370
	21st to end	Day	39% 25% 25% 9% 2	370
December	1st to 10th	Day	35% 21% 28% 12% 4	370
	11th to 20th	Day	37% 27% 25% 8% 2	370
	21st to end	Day	29% 24% 30% 12% 4 1	407
January	1st to 10th	Night	32% 25% 29% 11% 3	850
	11th to 20th	Night	33% 23% 28% 12% 3	818
	21st to end	Night	30% 23% 29% 16% 2	880
February	1st to 10th	Night	32% 27% 31% 10% 1	800
	11th to 20th	Night	36% 24% 27% 10% 2	775
	21st to end	Night	25% 26% 29% 16% 4	592
March	1st to 10th	Night	25% 30% 29% 12% 3	714
	11th to 20th	Night	25% 21% 27% 21% 6%	540
	21st to end	Night	34% 21% 28% 15% 3	594
April	1st to 10th	Night	32% 22% 26% 15% 5%	540
	11th to 20th	Night	32% 18% 32% 15% 4	534
	21st to end	Night	37% 16% 28% 16% 3 1	540
May	1st to 10th	Night	34% 13% 30% 19% 4	540
	11th to 20th	Night	31% 14% 28% 20% 6%	532
	21st to end	Night	34% 16% 28% 19% 4	583
June	1st to 10th	Night	37% 14% 27% 18% 4	540
	11th to 20th	Night	32% 12% 28% 22% 6%	540
	21st to end	Night	34% 11% 32% 17% 5% 1	540
July	1st to 10th	Night	28% 12% 33% 23% 4 1	526
	11th to 20th	Night	31% 11% 36% 19% 3	522
	21st to end	Night	31% 11% 33% 20% 6%	590
August	1st to 10th	Night	31% 8% 29% 25% 7%	538
	11th to 20th	Night	28% 12% 29% 24% 6%	532
	21st to end	Night	28% 8% 32% 25% 7%	594
September	1st to 10th	Night	27% 8% 32% 26% 7%	540
	11th to 20th	Night	34% 12% 30% 19% 5% 1	540
	21st to end	Night	29% 14% 29% 24% 5%	540
October	1st to 10th	Night	30% 14% 30% 21% 4	582
	11th to 20th	Night	34% 15% 27% 17% 6%	679
	21st to end	Night	36% 18% 25% 17% 4	891
November	1st to 10th	Night	33% 22% 26% 16% 3	830
	11th to 20th	Night	35% 17% 26% 17% 4	850
	21st to end	Night	33% 25% 28% 11% 4	850
December	1st to 10th	Night	33% 22% 27% 15% 4	850
	11th to 20th	Night	38% 26% 24% 10% 2	850
	21st to end	Night	30% 23% 29% 14% 3 1	935

Page generated at 2024-01-11 05:22:37. Version ac07

Copyright 2024 Attilla Danko