Windy Point Observation Site
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Windy Point Observation Site clear sky chart from 2005-11-06 to 2025-02-25.

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	4 7% 3 9% 5% 5% 5% 4 5% 6% 47%	112708
	Night	1 4 2 6% 4 4 4 4 6% 8% 57%	114831
Transparency	Day	34% 7% 10% 19% 21% 9%	112466
	Night	22% 8% 13% 23% 25% 10%	114662
Seeing	Day	18% 21% 26% 21% 11% 3	15651
	Night	7% 12% 28% 32% 18% 3	25929

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 3 13% 6% 4 4 4 6% 8% 51%	3895
	11th to 20th	Day	2 3 8% 6% 6% 4 3 5% 9% 53%	4100
	21st to end	Day	5% 4 10% 5% 5% 4 3 5% 7% 52%	4510
February	1st to 10th	Day	4 4 13% 5% 3 4 3 5% 7% 52%	1800
	11th to 20th	Day	4 4 10% 6% 5% 4 4 6% 9% 48%	1831
	21st to end	Day	4 4 13% 5% 5% 5% 3 5% 6% 49%	1610
March	1st to 10th	Day	6% 6% 13% 6% 4 4 3 4 6% 48%	3384
	11th to 20th	Day	1 11% 8% 16% 6% 4 5% 3 4 6% 36%	3490
	21st to end	Day	1 14% 7% 14% 6% 5% 5% 3 4 5% 35%	3876
April	1st to 10th	Day	2 9% 3 8% 6% 4 5% 4 6% 6% 48%	2280
	11th to 20th	Day	2 10% 5% 9% 6% 5% 5% 3 5% 7% 43%	2251
	21st to end	Day	1 10% 5% 7% 5% 5% 5% 4 6% 7% 45%	2280
May	1st to 10th	Day	2 11% 4 9% 6% 5% 4 4 5% 6% 43%	3951
	11th to 20th	Day	3 8% 3 8% 6% 6% 6% 5% 8% 7% 41%	4184
	21st to end	Day	3 6% 2 7% 5% 5% 6% 5% 6% 7% 47%	4825
June	1st to 10th	Day	4 5% 2 7% 5% 5% 5% 4 6% 7% 50%	2660
	11th to 20th	Day	5% 5% 2 7% 5% 4 5% 3 5% 5% 55%	2660
	21st to end	Day	5% 6% 3 7% 5% 6% 5% 4 5% 6% 48%	2660
July	1st to 10th	Day	6% 5% 2 7% 5% 5% 4 3 4 4 54%	4430
	11th to 20th	Day	7% 6% 3 8% 8% 8% 9% 6% 8% 7% 30%	4154
	21st to end	Day	10% 8% 3 11% 7% 6% 5% 5% 5% 6% 34%	4454
August	1st to 10th	Day	12% 10% 4 11% 7% 7% 7% 5% 6% 9% 23%	4092
	11th to 20th	Day	8% 8% 3 10% 7% 7% 7% 5% 6% 6% 32%	3853
	21st to end	Day	9% 9% 5% 12% 7% 7% 6% 5% 6% 7% 28%	4180
September	1st to 10th	Day	11% 8% 3 9% 6% 5% 5% 4 5% 5% 39%	2280
	11th to 20th	Day	9% 7% 4 8% 4 5% 5% 3 4 5% 47%	2280
	21st to end	Day	7% 8% 3 7% 4 4 3 3 4 5% 54%	2013
October	1st to 10th	Day	6% 7% 3 6% 4 3 3 2 3 4 58%	3170
	11th to 20th	Day	4 11% 3 9% 5% 4 4 3 4 5% 47%	3150
	21st to end	Day	2 5% 2 5% 3 2 3 2 3 5% 68%	3438
November	1st to 10th	Day	1 5% 2 5% 3 3 3 2 4 5% 67%	1897
	11th to 20th	Day	4 1 4 3 2 2 3 4 6% 71%	1800
	21st to end	Day	5% 2 7% 4 3 3 3 4 6% 63%	1620
December	1st to 10th	Day	4 2 4 4 3 2 2 3 8% 68%	2620
	11th to 20th	Day	3 1 7% 3 3 3 3 4 7% 64%	3026
	21st to end	Day	4 2 9% 4 3 4 3 6% 8% 57%	4004
January	1st to 10th	Night	1 1 9% 8% 7% 6% 5% 7% 9% 46%	6100
	11th to 20th	Night	2 1 7% 6% 5% 4 3 6% 7% 58%	5880
	21st to end	Night	3 3 7% 5% 5% 5% 4 6% 7% 56%	6468
February	1st to 10th	Night	2 2 9% 5% 4 4 3 5% 7% 59%	2600
	11th to 20th	Night	2 2 7% 4 5% 5% 4 6% 8% 57%	2454
	21st to end	Night	3 2 7% 4 6% 5% 3 5% 7% 59%	1938
March	1st to 10th	Night	3 4 6% 5% 5% 4 4 5% 8% 56%	3474
	11th to 20th	Night	6% 5% 13% 6% 5% 4 4 6% 8% 42%	3490
	21st to end	Night	6% 3 10% 6% 6% 6% 4 7% 8% 43%	3774
April	1st to 10th	Night	5% 2 5% 3 5% 4 4 7% 8% 57%	1900
	11th to 20th	Night	1 6% 3 6% 4 5% 5% 4 5% 8% 52%	1877
	21st to end	Night	1 5% 2 6% 4 4 4 3 6% 7% 57%	1900
May	1st to 10th	Night	1 9% 2 5% 4 3 4 3 5% 7% 57%	3015
	11th to 20th	Night	2 5% 2 4 3 3 4 4 6% 9% 57%	2717
	21st to end	Night	2 5% 2 3 2 2 2 3 4 6% 69%	2762
June	1st to 10th	Night	1 3 1 3 3 3 3 4 6% 7% 67%	1520
	11th to 20th	Night	2 3 1 2 3 2 4 3 4 7% 69%	1520
	21st to end	Night	2 2 1 3 3 4 4 5% 6% 7% 61%	1520
July	1st to 10th	Night	3 4 1 4 3 3 4 4 5% 6% 64%	2540
	11th to 20th	Night	2 2 1 5% 4 4 4 5% 8% 12% 53%	2811
	21st to end	Night	4 4 2 7% 6% 5% 6% 5% 8% 9% 45%	3109
August	1st to 10th	Night	5% 5% 2 7% 5% 6% 7% 5% 9% 13% 35%	2847
	11th to 20th	Night	4 3 1 4 3 4 5% 5% 9% 11% 50%	2986
	21st to end	Night	5% 6% 3 9% 5% 5% 6% 5% 6% 9% 41%	3487
September	1st to 10th	Night	4 4 2 6% 4 4 5% 4 7% 8% 51%	1900
	11th to 20th	Night	4 4 2 5% 3 3 4 4 6% 9% 58%	1900
	21st to end	Night	3 4 1 3 3 3 3 3 4 6% 66%	2162
October	1st to 10th	Night	3 4 1 3 2 2 2 2 3 5% 74%	3800
	11th to 20th	Night	2 6% 2 6% 4 4 3 3 4 6% 59%	3778
	21st to end	Night	1 4 1 4 3 3 2 2 4 6% 70%	4120
November	1st to 10th	Night	1 4 2 4 3 3 3 3 4 8% 64%	2380
	11th to 20th	Night	3 1 3 2 3 3 3 4 6% 73%	2600
	21st to end	Night	4 3 7% 4 3 2 3 6% 6% 61%	2777
December	1st to 10th	Night	1 1 3 3 3 3 2 3 6% 74%	4570
	11th to 20th	Night	3 1 4 3 3 3 3 5% 9% 67%	5181
	21st to end	Night	3 2 8% 5% 4 4 4 6% 8% 55%	6974

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	28% 6% 16% 22% 20% 9%	3896
	11th to 20th	Day	25% 6% 15% 17% 22% 15%	4100
	21st to end	Day	27% 8% 8% 23% 24% 11%	4510
February	1st to 10th	Day	32% 5% 14% 21% 17% 11%	1800
	11th to 20th	Day	32% 6% 9% 20% 24% 10%	1840
	21st to end	Day	34% 5% 8% 19% 22% 12%	1610
March	1st to 10th	Day	34% 6% 9% 20% 21% 10%	3384
	11th to 20th	Day	43% 9% 9% 25% 12% 3	3490
	21st to end	Day	49% 6% 9% 18% 15% 3	3876
April	1st to 10th	Day	33% 7% 12% 21% 20% 8%	2280
	11th to 20th	Day	38% 6% 10% 21% 19% 5%	2254
	21st to end	Day	36% 6% 12% 26% 16% 3	2280
May	1st to 10th	Day	36% 6% 13% 18% 20% 8%	3951
	11th to 20th	Day	34% 9% 13% 21% 18% 5%	4187
	21st to end	Day	26% 8% 12% 18% 30% 5%	4825
June	1st to 10th	Day	29% 7% 11% 23% 21% 9%	2660
	11th to 20th	Day	28% 6% 8% 17% 25% 16%	2660
	21st to end	Day	33% 7% 8% 16% 23% 14%	2660
July	1st to 10th	Day	31% 6% 7% 8% 15% 33%	4361
	11th to 20th	Day	41% 13% 13% 16% 12% 5%	4083
	21st to end	Day	43% 12% 12% 11% 13% 9%	4314
August	1st to 10th	Day	55% 10% 14% 8% 9% 3	4078
	11th to 20th	Day	47% 11% 11% 11% 15% 5%	3892
	21st to end	Day	49% 10% 10% 12% 15% 4	4179
September	1st to 10th	Day	44% 7% 10% 12% 19% 8%	2280
	11th to 20th	Day	38% 7% 8% 15% 23% 9%	2280
	21st to end	Day	33% 4 7% 19% 29% 8%	2013
October	1st to 10th	Day	28% 5% 5% 17% 33% 11%	3170
	11th to 20th	Day	35% 7% 7% 19% 25% 7%	3150
	21st to end	Day	20% 3 6% 22% 39% 10%	3438
November	1st to 10th	Day	19% 4 10% 23% 31% 11%	1897
	11th to 20th	Day	16% 4 9% 29% 31% 11%	1800
	21st to end	Day	23% 5% 9% 23% 26% 14%	1620
December	1st to 10th	Day	16% 5% 11% 29% 29% 10%	2620
	11th to 20th	Day	20% 6% 12% 28% 28% 7%	3024
	21st to end	Day	22% 6% 11% 22% 25% 13%	4004
January	1st to 10th	Night	24% 10% 13% 23% 21% 8%	6100
	11th to 20th	Night	16% 8% 17% 22% 21% 17%	5880
	21st to end	Night	21% 8% 8% 23% 26% 13%	6468
February	1st to 10th	Night	24% 6% 16% 21% 22% 11%	2600
	11th to 20th	Night	22% 7% 12% 24% 25% 10%	2455
	21st to end	Night	23% 7% 9% 22% 28% 11%	1938
March	1st to 10th	Night	23% 5% 12% 22% 35% 3	3474
	11th to 20th	Night	34% 9% 13% 26% 14% 3	3490
	21st to end	Night	34% 9% 13% 25% 17% 2	3774
April	1st to 10th	Night	21% 8% 16% 24% 23% 7%	1900
	11th to 20th	Night	26% 8% 12% 26% 23% 5%	1877
	21st to end	Night	23% 9% 14% 33% 20% 3	1900
May	1st to 10th	Night	23% 5% 12% 21% 34% 4	3015
	11th to 20th	Night	21% 7% 13% 33% 23% 2	2718
	21st to end	Night	15% 4 10% 25% 37% 9%	2762
June	1st to 10th	Night	14% 6% 13% 29% 30% 8%	1520
	11th to 20th	Night	15% 5% 9% 20% 33% 18%	1520
	21st to end	Night	19% 5% 10% 21% 27% 17%	1520
July	1st to 10th	Night	21% 6% 10% 10% 19% 34%	2500
	11th to 20th	Night	19% 9% 20% 30% 16% 6%	2759
	21st to end	Night	29% 13% 20% 18% 10% 10%	3011
August	1st to 10th	Night	34% 15% 24% 11% 12% 4	2838
	11th to 20th	Night	23% 12% 25% 12% 20% 7%	3013
	21st to end	Night	38% 10% 14% 17% 17% 5%	3487
September	1st to 10th	Night	27% 9% 16% 17% 24% 7%	1900
	11th to 20th	Night	22% 8% 13% 21% 27% 10%	1900
	21st to end	Night	19% 5% 8% 29% 32% 7%	2162
October	1st to 10th	Night	15% 3 8% 20% 39% 14%	3800
	11th to 20th	Night	20% 10% 9% 29% 26% 6%	3778
	21st to end	Night	15% 5% 6% 22% 40% 11%	4120
November	1st to 10th	Night	19% 5% 12% 24% 29% 10%	2380
	11th to 20th	Night	12% 5% 9% 30% 32% 11%	2600
	21st to end	Night	22% 5% 9% 23% 28% 13%	2777
December	1st to 10th	Night	12% 4 11% 30% 32% 10%	4570
	11th to 20th	Night	14% 7% 10% 27% 32% 10%	5182
	21st to end	Night	22% 8% 12% 21% 24% 12%	6974

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	18% 20% 32% 20% 9% 1	300
	11th to 20th	Day	21% 25% 23% 26% 5%	300
	21st to end	Day	12% 24% 30% 25% 7% 1	330
February	1st to 10th	Day	22% 33% 29% 14% 1 1	300
	11th to 20th	Day	23% 35% 24% 14% 5%	300
	21st to end	Day	27% 34% 21% 16% 3	237
March	1st to 10th	Day	26% 31% 23% 17% 4	422
	11th to 20th	Day	21% 28% 28% 16% 6% 1	460
	21st to end	Day	29% 32% 26% 11% 2	506
April	1st to 10th	Day	24% 30% 28% 13% 4 1	460
	11th to 20th	Day	29% 34% 25% 8% 4 1	452
	21st to end	Day	24% 33% 26% 13% 4 1	460
May	1st to 10th	Day	23% 35% 28% 9% 5%	463
	11th to 20th	Day	17% 28% 30% 17% 7% 2	549
	21st to end	Day	20% 23% 24% 19% 11% 3	734
June	1st to 10th	Day	10% 16% 27% 27% 16% 4	680
	11th to 20th	Day	11% 19% 29% 23% 14% 3	680
	21st to end	Day	6% 18% 28% 23% 20% 5%	680
July	1st to 10th	Day	9% 9% 22% 31% 23% 6%	671
	11th to 20th	Day	13% 6% 20% 32% 22% 7%	513
	21st to end	Day	19% 7% 19% 29% 18% 6%	531
August	1st to 10th	Day	20% 12% 20% 25% 17% 6%	487
	11th to 20th	Day	12% 11% 23% 32% 15% 6%	477
	21st to end	Day	14% 11% 28% 26% 18% 4	539
September	1st to 10th	Day	14% 14% 23% 26% 15% 8%	490
	11th to 20th	Day	15% 18% 30% 22% 11% 3	490
	21st to end	Day	18% 18% 23% 20% 14% 6%	380
October	1st to 10th	Day	18% 19% 21% 20% 17% 6%	300
	11th to 20th	Day	16% 23% 26% 20% 13% 3	300
	21st to end	Day	17% 23% 25% 23% 12% 2	330
November	1st to 10th	Day	20% 24% 24% 21% 9% 2	300
	11th to 20th	Day	14% 26% 27% 23% 9% 2	300
	21st to end	Day	16% 23% 28% 19% 12% 2	300
December	1st to 10th	Day	16% 22% 30% 17% 12% 2	300
	11th to 20th	Day	17% 25% 28% 22% 7% 1	300
	21st to end	Day	23% 23% 29% 19% 3 2	330
January	1st to 10th	Night	7% 15% 32% 31% 13% 2	903
	11th to 20th	Night	8% 15% 34% 29% 13% 1	800
	21st to end	Night	5% 12% 37% 34% 9% 3	880
February	1st to 10th	Night	7% 17% 40% 29% 7% 1	800
	11th to 20th	Night	7% 16% 44% 26% 8%	784
	21st to end	Night	9% 14% 44% 27% 4	646
March	1st to 10th	Night	9% 19% 33% 30% 9% 1	760
	11th to 20th	Night	6% 14% 34% 30% 15% 1	760
	21st to end	Night	9% 16% 38% 30% 7%	807
April	1st to 10th	Night	9% 21% 36% 28% 6%	570
	11th to 20th	Night	11% 19% 34% 28% 9%	563
	21st to end	Night	6% 19% 34% 29% 11% 1	570
May	1st to 10th	Night	8% 14% 35% 31% 12%	570
	11th to 20th	Night	7% 11% 26% 36% 17% 3	561
	21st to end	Night	11% 14% 27% 27% 19% 2	617
June	1st to 10th	Night	3 9% 21% 40% 25% 1	570
	11th to 20th	Night	7% 10% 23% 39% 18% 2	570
	21st to end	Night	3 5% 18% 39% 32% 3	570
July	1st to 10th	Night	5% 2 12% 37% 40% 3	555
	11th to 20th	Night	4 1 8% 31% 47% 9%	552
	21st to end	Night	7% 1 4 32% 48% 8%	624
August	1st to 10th	Night	8% 2 8% 29% 47% 6%	567
	11th to 20th	Night	8% 2 9% 34% 43% 5%	564
	21st to end	Night	7% 4 9% 34% 39% 6%	627
September	1st to 10th	Night	5% 3 13% 37% 37% 4	570
	11th to 20th	Night	5% 5% 19% 36% 30% 4	570
	21st to end	Night	8% 8% 16% 32% 28% 7%	723
October	1st to 10th	Night	8% 12% 23% 34% 20% 3	760
	11th to 20th	Night	6% 11% 30% 32% 18% 4	760
	21st to end	Night	8% 11% 24% 35% 17% 4	836
November	1st to 10th	Night	7% 13% 29% 31% 18% 2	820
	11th to 20th	Night	7% 13% 34% 32% 11% 2	1000
	21st to end	Night	10% 14% 29% 33% 13% 2	1000
December	1st to 10th	Night	6% 14% 37% 31% 10% 1	1000
	11th to 20th	Night	8% 19% 36% 26% 10% 1	1000
	21st to end	Night	9% 14% 40% 29% 6% 1	1100

Page generated at 2025-02-22 04:51:33. Version ac07

Copyright © 2025 Attilla Danko.