Stock Dr/Savery
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Stock Dr/Savery clear sky chart from 2005-11-06 to 2024-11-12.

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	5% 11% 4 7% 4 4 4 3 5% 6% 46%	105405
	Night	6% 12% 4 8% 4 4 4 3 5% 6% 46%	102521
Transparency	Day	19% 47% 5% 13% 11% 5%	105157
	Night	20% 48% 6% 12% 10% 4	102359
Seeing	Day	14% 18% 31% 24% 12% 2	15642
	Night	13% 11% 29% 32% 14% 2	25712

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% 16% 8% 17% 5% 3 3 2 4 5% 31%	2538
	11th to 20th	Day	8% 22% 7% 14% 7% 3 3 3 4 4 24%	2764
	21st to end	Day	3 27% 7% 12% 5% 3 3 2 3 4 31%	3146
February	1st to 10th	Day	8% 22% 7% 13% 4 3 4 3 3 5% 28%	1710
	11th to 20th	Day	8% 22% 8% 11% 4 3 3 2 3 4 31%	1674
	21st to end	Day	5% 19% 6% 15% 5% 3 4 3 4 5% 30%	1570
March	1st to 10th	Day	4 17% 8% 13% 6% 4 4 3 4 6% 32%	3319
	11th to 20th	Day	3 14% 4 7% 4 4 3 3 4 5% 50%	3490
	21st to end	Day	6% 25% 7% 11% 5% 3 4 3 5% 6% 24%	3904
April	1st to 10th	Day	8% 17% 4 8% 5% 4 4 3 6% 7% 36%	2280
	11th to 20th	Day	8% 17% 4 9% 4 4 4 4 5% 4 35%	2251
	21st to end	Day	7% 14% 4 7% 5% 5% 5% 4 5% 6% 39%	2302
May	1st to 10th	Day	10% 18% 6% 9% 5% 4 5% 4 5% 6% 28%	4142
	11th to 20th	Day	5% 6% 2 6% 5% 4 5% 4 7% 9% 46%	4388
	21st to end	Day	8% 8% 2 7% 5% 5% 5% 4 6% 7% 44%	4825
June	1st to 10th	Day	5% 5% 2 5% 4 5% 4 4 7% 8% 51%	2660
	11th to 20th	Day	5% 3 2 5% 3 4 5% 4 6% 7% 58%	2660
	21st to end	Day	3 2 1 4 3 4 4 4 6% 7% 63%	2660
July	1st to 10th	Day	3 2 1 3 3 3 4 3 6% 8% 64%	4430
	11th to 20th	Day	1 2 2 5% 5% 5% 5% 5% 8% 10% 53%	4430
	21st to end	Day	2 3 1 4 4 4 5% 4 6% 8% 57%	4527
August	1st to 10th	Day	2 3 2 5% 4 5% 5% 5% 8% 9% 52%	4092
	11th to 20th	Day	5% 4 1 5% 4 4 5% 4 6% 8% 54%	3976
	21st to end	Day	3 4 1 4 4 4 5% 4 6% 7% 59%	4180
September	1st to 10th	Day	4 3 1 3 4 3 4 4 5% 6% 63%	2280
	11th to 20th	Day	5% 5% 1 4 3 3 4 3 5% 6% 58%	2280
	21st to end	Day	7% 5% 2 4 3 2 3 3 5% 5% 62%	2012
October	1st to 10th	Day	5% 5% 1 3 2 3 2 2 3 4 69%	3170
	11th to 20th	Day	7% 8% 3 4 3 3 3 3 5% 7% 54%	3150
	21st to end	Day	8% 13% 3 6% 3 2 3 3 4 6% 50%	3438
November	1st to 10th	Day	8% 11% 3 7% 2 3 3 3 5% 8% 46%	1792
	11th to 20th	Day	10% 13% 5% 7% 4 3 3 3 5% 5% 43%	1605
	21st to end	Day	6% 12% 5% 9% 4 4 2 3 3 6% 46%	1520
December	1st to 10th	Day	8% 20% 6% 12% 6% 3 3 4 3 5% 31%	1520
	11th to 20th	Day	7% 19% 5% 11% 4 3 3 2 4 6% 36%	1926
	21st to end	Day	6% 18% 6% 11% 6% 4 3 2 4 6% 33%	2794
January	1st to 10th	Night	5% 16% 7% 17% 8% 5% 3 2 4 4 30%	4417
	11th to 20th	Night	6% 24% 7% 16% 5% 3 2 2 3 4 28%	4236
	21st to end	Night	5% 24% 7% 11% 5% 3 3 2 3 4 32%	4521
February	1st to 10th	Night	8% 18% 7% 14% 5% 4 3 3 4 5% 28%	2470
	11th to 20th	Night	6% 19% 7% 10% 4 4 3 3 4 5% 33%	2392
	21st to end	Night	4 19% 7% 11% 5% 4 3 3 4 6% 33%	1884
March	1st to 10th	Night	5% 14% 7% 12% 4 4 4 3 4 6% 39%	3548
	11th to 20th	Night	4 12% 4 6% 3 3 3 3 4 5% 52%	3490
	21st to end	Night	6% 23% 6% 10% 4 4 4 3 5% 5% 30%	3745
April	1st to 10th	Night	8% 16% 3 6% 4 4 3 4 5% 6% 42%	1900
	11th to 20th	Night	9% 13% 4 8% 5% 4 5% 4 5% 6% 38%	1877
	21st to end	Night	9% 12% 3 6% 4 4 4 3 6% 6% 42%	1875
May	1st to 10th	Night	8% 16% 4 8% 5% 4 5% 4 5% 6% 37%	2811
	11th to 20th	Night	8% 8% 2 7% 4 4 5% 4 7% 8% 43%	2517
	21st to end	Night	9% 9% 2 6% 4 4 4 3 5% 7% 47%	2762
June	1st to 10th	Night	5% 5% 1 4 3 3 4 5% 6% 9% 55%	1520
	11th to 20th	Night	5% 4 2 4 4 4 5% 4 6% 6% 56%	1520
	21st to end	Night	2 3 1 4 3 4 3 3 4 6% 67%	1520
July	1st to 10th	Night	3 3 1 4 2 3 4 3 5% 6% 64%	2540
	11th to 20th	Night	2 3 2 6% 5% 4 5% 5% 8% 10% 51%	2540
	21st to end	Night	1 2 1 4 4 5% 6% 5% 7% 8% 57%	3033
August	1st to 10th	Night	2 3 1 4 4 4 5% 5% 6% 9% 57%	2847
	11th to 20th	Night	3 4 2 6% 5% 5% 6% 4 7% 8% 50%	2863
	21st to end	Night	3 3 1 3 3 4 5% 5% 8% 9% 57%	3487
September	1st to 10th	Night	5% 4 1 3 2 2 3 3 5% 7% 64%	1900
	11th to 20th	Night	5% 5% 1 4 3 3 5% 3 5% 6% 60%	1900
	21st to end	Night	6% 3 1 2 2 2 3 3 4 5% 68%	2164
October	1st to 10th	Night	5% 5% 1 3 2 2 2 2 3 5% 71%	3800
	11th to 20th	Night	7% 6% 1 4 3 3 4 3 5% 7% 56%	3778
	21st to end	Night	7% 11% 3 6% 3 2 3 3 3 6% 52%	4120
November	1st to 10th	Night	10% 12% 3 5% 2 3 3 3 6% 5% 49%	2487
	11th to 20th	Night	9% 13% 3 7% 3 3 3 3 4 6% 44%	2593
	21st to end	Night	6% 14% 5% 8% 4 3 3 3 4 7% 45%	2660
December	1st to 10th	Night	9% 18% 5% 9% 4 4 3 2 4 5% 37%	2660
	11th to 20th	Night	8% 16% 6% 9% 4 3 4 3 4 6% 38%	3271
	21st to end	Night	5% 16% 5% 11% 5% 4 4 3 5% 6% 35%	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	38% 38% 7% 11% 6% 1	2539
	11th to 20th	Day	44% 38% 9% 6% 3 1	2764
	21st to end	Day	34% 42% 9% 12% 4	3146
February	1st to 10th	Day	24% 66% 3 5% 2	1710
	11th to 20th	Day	19% 64% 5% 8% 3 1	1683
	21st to end	Day	20% 64% 4 7% 4	1570
March	1st to 10th	Day	28% 43% 9% 11% 8%	3319
	11th to 20th	Day	19% 41% 7% 27% 5%	3490
	21st to end	Day	36% 44% 5% 11% 3 1	3904
April	1st to 10th	Day	17% 65% 5% 7% 5% 1	2280
	11th to 20th	Day	18% 66% 3 8% 5% 1	2254
	21st to end	Day	17% 66% 4 10% 4	2302
May	1st to 10th	Day	34% 42% 5% 8% 9% 1	4142
	11th to 20th	Day	15% 43% 8% 20% 13% 1	4392
	21st to end	Day	19% 42% 5% 18% 15% 1	4825
June	1st to 10th	Day	7% 65% 4 9% 12% 3	2660
	11th to 20th	Day	7% 65% 5% 8% 10% 5%	2660
	21st to end	Day	9% 64% 2 8% 12% 5%	2660
July	1st to 10th	Day	9% 37% 4 8% 20% 22%	4361
	11th to 20th	Day	14% 38% 4 11% 17% 16%	4355
	21st to end	Day	12% 37% 5% 9% 18% 20%	4384
August	1st to 10th	Day	15% 39% 5% 18% 12% 11%	4078
	11th to 20th	Day	18% 39% 6% 12% 19% 5%	4015
	21st to end	Day	15% 38% 6% 12% 15% 14%	4179
September	1st to 10th	Day	9% 60% 3 9% 13% 6%	2280
	11th to 20th	Day	8% 59% 3 12% 14% 4	2280
	21st to end	Day	10% 59% 2 10% 14% 4	2012
October	1st to 10th	Day	7% 36% 3 12% 31% 10%	3170
	11th to 20th	Day	17% 37% 3 23% 17% 3	3150
	21st to end	Day	22% 37% 6% 24% 10% 1	3438
November	1st to 10th	Day	17% 57% 5% 14% 6% 1	1792
	11th to 20th	Day	15% 59% 7% 12% 7% 1	1605
	21st to end	Day	21% 59% 5% 9% 6%	1520
December	1st to 10th	Day	27% 60% 5% 4 4	1520
	11th to 20th	Day	19% 50% 6% 20% 5%	1924
	21st to end	Day	27% 38% 8% 16% 9% 1	2794
January	1st to 10th	Night	39% 38% 6% 11% 5% 1	4417
	11th to 20th	Night	43% 39% 8% 5% 3 2	4236
	21st to end	Night	33% 43% 10% 8% 6%	4521
February	1st to 10th	Night	25% 65% 3 4 3	2470
	11th to 20th	Night	18% 64% 5% 8% 4 1	2393
	21st to end	Night	17% 65% 5% 7% 5% 1	1884
March	1st to 10th	Night	25% 43% 7% 14% 10% 1	3548
	11th to 20th	Night	18% 41% 10% 24% 7% 1	3490
	21st to end	Night	32% 45% 5% 14% 3 1	3745
April	1st to 10th	Night	14% 65% 6% 9% 5% 1	1900
	11th to 20th	Night	15% 67% 4 8% 5% 1	1877
	21st to end	Night	13% 66% 5% 10% 5%	1875
May	1st to 10th	Night	28% 42% 6% 12% 11% 1	2811
	11th to 20th	Night	19% 46% 8% 17% 7% 4	2518
	21st to end	Night	19% 43% 4 21% 12% 1	2762
June	1st to 10th	Night	4 65% 4 12% 10% 5%	1520
	11th to 20th	Night	9% 66% 4 8% 9% 4	1520
	21st to end	Night	8% 63% 2 9% 13% 5%	1520
July	1st to 10th	Night	11% 37% 3 8% 19% 22%	2500
	11th to 20th	Night	16% 37% 5% 15% 16% 11%	2492
	21st to end	Night	12% 36% 4 11% 22% 14%	2938
August	1st to 10th	Night	13% 39% 6% 17% 12% 13%	2838
	11th to 20th	Night	23% 41% 7% 11% 13% 6%	2890
	21st to end	Night	15% 40% 7% 9% 17% 13%	3487
September	1st to 10th	Night	7% 60% 3 8% 14% 7%	1900
	11th to 20th	Night	9% 60% 3 10% 14% 4	1900
	21st to end	Night	9% 60% 2 11% 14% 5%	2164
October	1st to 10th	Night	8% 36% 2 9% 32% 12%	3800
	11th to 20th	Night	17% 38% 3 21% 18% 2	3778
	21st to end	Night	22% 38% 7% 21% 11% 2	4120
November	1st to 10th	Night	17% 56% 6% 11% 9% 1	2487
	11th to 20th	Night	15% 60% 4 13% 8% 1	2593
	21st to end	Night	20% 60% 4 9% 6%	2660
December	1st to 10th	Night	24% 61% 5% 6% 4	2660
	11th to 20th	Night	16% 51% 7% 20% 6%	3272
	21st to end	Night	26% 39% 9% 16% 10% 1	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	26% 22% 24% 20% 8% 1	270
	11th to 20th	Day	22% 26% 32% 15% 4	270
	21st to end	Day	16% 27% 39% 13% 4 1	297
February	1st to 10th	Day	27% 33% 28% 11% 1	270
	11th to 20th	Day	27% 28% 26% 18% 1	270
	21st to end	Day	25% 31% 32% 10% 2	225
March	1st to 10th	Day	21% 33% 30% 13% 4	381
	11th to 20th	Day	13% 29% 35% 18% 4	460
	21st to end	Day	22% 28% 36% 12% 2	506
April	1st to 10th	Day	19% 31% 30% 16% 4	460
	11th to 20th	Day	22% 30% 32% 12% 4	452
	21st to end	Day	20% 21% 29% 22% 8% 1	460
May	1st to 10th	Day	18% 21% 35% 18% 7% 1	482
	11th to 20th	Day	16% 10% 29% 25% 17% 2	675
	21st to end	Day	15% 14% 29% 23% 17% 2	734
June	1st to 10th	Day	7% 11% 28% 30% 20% 5%	680
	11th to 20th	Day	9% 16% 34% 27% 13% 1	680
	21st to end	Day	6% 10% 31% 30% 19% 3	680
July	1st to 10th	Day	4 7% 24% 37% 24% 4	671
	11th to 20th	Day	2 6% 29% 35% 23% 5%	668
	21st to end	Day	4 5% 26% 40% 20% 4	578
August	1st to 10th	Day	6% 7% 38% 33% 14% 3	487
	11th to 20th	Day	4 8% 34% 34% 17% 4	477
	21st to end	Day	5% 9% 34% 30% 18% 4	539
September	1st to 10th	Day	7% 11% 29% 29% 19% 5%	490
	11th to 20th	Day	11% 14% 35% 23% 14% 3	490
	21st to end	Day	11% 18% 28% 27% 12% 5%	380
October	1st to 10th	Day	13% 15% 27% 27% 14% 4	300
	11th to 20th	Day	19% 20% 29% 22% 8% 2	300
	21st to end	Day	21% 23% 32% 19% 5% 1	330
November	1st to 10th	Day	21% 28% 30% 15% 6% 1	300
	11th to 20th	Day	21% 24% 36% 17% 3 1	273
	21st to end	Day	14% 24% 41% 17% 3 1	270
December	1st to 10th	Day	24% 26% 26% 18% 5% 1	270
	11th to 20th	Day	19% 28% 36% 14% 3	270
	21st to end	Day	24% 24% 32% 16% 4 1	297
January	1st to 10th	Night	19% 15% 32% 26% 8% 1	950
	11th to 20th	Night	18% 16% 35% 24% 6% 1	834
	21st to end	Night	14% 15% 38% 25% 6% 1	836
February	1st to 10th	Night	17% 17% 41% 20% 5% 1	760
	11th to 20th	Night	15% 16% 37% 27% 5%	744
	21st to end	Night	15% 19% 39% 23% 4	628
March	1st to 10th	Night	16% 15% 33% 27% 8% 1	760
	11th to 20th	Night	11% 10% 32% 38% 9% 1	760
	21st to end	Night	12% 13% 38% 28% 8% 1	791
April	1st to 10th	Night	15% 16% 31% 32% 6%	570
	11th to 20th	Night	16% 15% 33% 27% 9% 1	563
	21st to end	Night	15% 11% 26% 34% 12% 2	570
May	1st to 10th	Night	15% 11% 29% 31% 14% 1	570
	11th to 20th	Night	12% 3 21% 43% 19% 2	561
	21st to end	Night	12% 8% 21% 38% 18% 2	617
June	1st to 10th	Night	6% 7% 22% 38% 25% 2	570
	11th to 20th	Night	7% 6% 30% 42% 15%	570
	21st to end	Night	4 3 19% 47% 25% 2	570
July	1st to 10th	Night	6% 3 14% 41% 34% 3	555
	11th to 20th	Night	4 1 13% 47% 31% 3	552
	21st to end	Night	3 1 9% 46% 38% 3	624
August	1st to 10th	Night	6% 1 13% 49% 31% 1	567
	11th to 20th	Night	5% 2 16% 45% 31% 2	564
	21st to end	Night	5% 2 14% 42% 31% 5%	627
September	1st to 10th	Night	7% 2 17% 44% 25% 5%	570
	11th to 20th	Night	8% 4 21% 40% 23% 4	570
	21st to end	Night	8% 5% 22% 34% 24% 7%	725
October	1st to 10th	Night	13% 7% 24% 37% 16% 2	760
	11th to 20th	Night	10% 11% 25% 39% 13% 2	760
	21st to end	Night	14% 11% 31% 31% 10% 2	836
November	1st to 10th	Night	15% 15% 34% 25% 10% 1	927
	11th to 20th	Night	16% 17% 38% 23% 5%	956
	21st to end	Night	13% 13% 38% 30% 6%	950
December	1st to 10th	Night	19% 16% 35% 24% 5%	950
	11th to 20th	Night	16% 18% 38% 21% 6%	950
	21st to end	Night	19% 20% 36% 19% 5% 1	1045

Page generated at 2024-11-08 20:45:35. Version ac07

Copyright © 2024 Attilla Danko.