Fickle Hill Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Fickle Hill Observatory clear sky chart from 2005-11-06 to 2024-11-04.

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	14% 8% 2 5% 4 3 3 3 4 6% 47%	105203
	Night	16% 9% 3 6% 4 4 4 3 4 6% 41%	102558
Transparency	Day	34% 7% 12% 20% 17% 10%	104960
	Night	39% 8% 13% 17% 14% 8%	102391
Seeing	Day	19% 11% 25% 28% 13% 4	15200
	Night	20% 6% 13% 29% 26% 6%	24258

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	31% 15% 3 7% 4 3 4 3 4 5% 22%	2640
	11th to 20th	Day	35% 11% 3 6% 4 3 4 2 3 4 24%	2860
	21st to end	Day	33% 10% 2 6% 4 3 3 3 5% 5% 25%	3146
February	1st to 10th	Day	21% 11% 2 5% 4 4 4 3 5% 7% 34%	1710
	11th to 20th	Day	23% 11% 3 6% 3 4 4 3 5% 7% 32%	1665
	21st to end	Day	25% 15% 3 6% 3 3 3 2 4 5% 32%	1534
March	1st to 10th	Day	29% 22% 3 6% 3 3 2 2 3 3 23%	3442
	11th to 20th	Day	19% 10% 2 5% 4 3 2 3 4 5% 44%	3490
	21st to end	Day	29% 14% 3 8% 5% 4 4 4 5% 5% 20%	3825
April	1st to 10th	Day	22% 14% 2 7% 5% 5% 5% 4 5% 6% 25%	2245
	11th to 20th	Day	22% 13% 2 6% 4 4 3 3 4 7% 32%	2249
	21st to end	Day	17% 11% 3 5% 4 3 4 3 6% 8% 36%	2418
May	1st to 10th	Day	16% 10% 2 4 3 3 3 2 4 5% 50%	4110
	11th to 20th	Day	9% 5% 1 4 2 2 2 2 3 6% 62%	4183
	21st to end	Day	10% 8% 2 5% 3 3 4 3 5% 8% 50%	4813
June	1st to 10th	Day	14% 10% 2 6% 4 4 5% 3 5% 7% 40%	2660
	11th to 20th	Day	8% 4 1 4 4 3 4 3 6% 7% 56%	2660
	21st to end	Day	6% 4 1 3 3 2 3 3 4 7% 65%	2660
July	1st to 10th	Day	2 2 1 2 2 2 2 2 3 4 78%	4420
	11th to 20th	Day	2 3 1 3 2 5% 4 2 3 5% 69%	4206
	21st to end	Day	2 1 4 5% 4 3 3 4 8% 64%	4455
August	1st to 10th	Day	1 2 1 4 5% 8% 6% 4 6% 9% 53%	4091
	11th to 20th	Day	2 4 2 5% 3 4 4 3 6% 7% 60%	4026
	21st to end	Day	5% 3 1 3 2 2 2 2 4 6% 69%	4256
September	1st to 10th	Day	4 3 1 3 2 2 2 2 4 7% 70%	2280
	11th to 20th	Day	6% 5% 2 5% 4 4 3 3 6% 7% 56%	2180
	21st to end	Day	7% 4 2 3 2 2 2 2 5% 7% 64%	2056
October	1st to 10th	Day	5% 3 2 3 2 2 3 2 3 5% 71%	3180
	11th to 20th	Day	10% 4 2 6% 4 5% 5% 4 6% 7% 47%	3161
	21st to end	Day	17% 7% 2 6% 4 4 4 4 6% 6% 40%	3448
November	1st to 10th	Day	22% 8% 2 6% 4 3 4 3 6% 9% 33%	1852
	11th to 20th	Day	22% 8% 2 5% 5% 3 5% 4 6% 9% 31%	1520
	21st to end	Day	19% 7% 3 7% 5% 4 3 3 5% 8% 36%	1520
December	1st to 10th	Day	21% 8% 3 6% 3 3 3 3 5% 8% 37%	1520
	11th to 20th	Day	28% 11% 3 8% 5% 4 4 3 5% 6% 23%	1928
	21st to end	Day	30% 12% 4 9% 6% 5% 4 3 3 4 21%	2794
January	1st to 10th	Night	28% 14% 3 8% 5% 4 4 4 5% 5% 20%	4304
	11th to 20th	Night	30% 13% 4 9% 5% 3 3 2 3 5% 23%	4110
	21st to end	Night	40% 13% 2 5% 3 2 3 2 3 4 22%	4521
February	1st to 10th	Night	20% 11% 4 7% 4 4 4 3 4 6% 33%	2470
	11th to 20th	Night	23% 11% 3 8% 5% 4 4 2 4 6% 31%	2402
	21st to end	Night	21% 13% 2 5% 4 4 4 4 4 8% 32%	1914
March	1st to 10th	Night	28% 21% 3 6% 3 3 3 3 5% 5% 23%	3432
	11th to 20th	Night	18% 11% 3 5% 3 3 2 2 4 6% 43%	3490
	21st to end	Night	25% 19% 4 8% 4 4 4 3 4 4 21%	3828
April	1st to 10th	Night	20% 14% 4 6% 5% 5% 4 3 5% 8% 27%	1933
	11th to 20th	Night	18% 13% 3 6% 4 4 4 3 6% 6% 33%	1879
	21st to end	Night	17% 10% 3 6% 4 4 3 3 7% 8% 35%	1760
May	1st to 10th	Night	12% 10% 3 6% 3 3 3 3 5% 6% 48%	2860
	11th to 20th	Night	7% 7% 2 5% 3 4 3 3 3 6% 57%	2716
	21st to end	Night	7% 10% 3 7% 5% 5% 4 3 4 4 46%	2762
June	1st to 10th	Night	13% 10% 3 7% 3 4 4 4 7% 8% 36%	1520
	11th to 20th	Night	6% 6% 2 6% 4 4 5% 3 4 8% 52%	1520
	21st to end	Night	5% 4 1 5% 3 4 5% 3 5% 7% 57%	1520
July	1st to 10th	Night	2 2 1 4 3 3 3 2 3 5% 72%	2540
	11th to 20th	Night	2 2 1 4 4 8% 6% 3 4 6% 60%	2756
	21st to end	Night	8% 3 6% 4 8% 6% 3 4 6% 52%	3109
August	1st to 10th	Night	3 2 10% 6% 12% 9% 4 4 6% 43%	2848
	11th to 20th	Night	2 5% 3 7% 4 7% 4 2 4 6% 55%	2812
	21st to end	Night	5% 2 1 4 2 3 4 3 3 7% 66%	3420
September	1st to 10th	Night	3 3 1 3 2 2 3 2 4 8% 71%	1900
	11th to 20th	Night	5% 5% 2 4 3 4 4 2 5% 8% 58%	1998
	21st to end	Night	7% 5% 2 4 3 3 3 3 5% 6% 60%	2123
October	1st to 10th	Night	5% 4 2 4 2 2 4 2 3 4 68%	3800
	11th to 20th	Night	12% 8% 3 7% 4 3 3 3 5% 7% 46%	3777
	21st to end	Night	15% 7% 2 7% 4 5% 5% 4 6% 8% 38%	4121
November	1st to 10th	Night	20% 9% 2 7% 4 4 4 4 5% 5% 35%	2295
	11th to 20th	Night	21% 9% 3 8% 5% 5% 4 3 5% 7% 29%	2660
	21st to end	Night	19% 8% 2 6% 4 3 4 4 5% 8% 37%	2660
December	1st to 10th	Night	23% 7% 2 6% 4 4 4 3 6% 7% 35%	2660
	11th to 20th	Night	29% 11% 3 7% 4 3 5% 3 5% 6% 23%	3276
	21st to end	Night	27% 12% 3 7% 4 5% 4 3 4 5% 26%	4862

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	62% 9% 9% 14% 3 3	2640
	11th to 20th	Day	64% 8% 6% 10% 7% 6%	2860
	21st to end	Day	59% 7% 10% 10% 9% 4	3146
February	1st to 10th	Day	50% 6% 11% 16% 11% 5%	1710
	11th to 20th	Day	51% 7% 10% 18% 12% 1	1674
	21st to end	Day	57% 5% 11% 17% 9% 2	1534
March	1st to 10th	Day	67% 6% 6% 15% 6% 1	3442
	11th to 20th	Day	41% 6% 17% 15% 17% 5%	3490
	21st to end	Day	62% 10% 15% 9% 3	3825
April	1st to 10th	Day	56% 9% 14% 13% 7% 1	2245
	11th to 20th	Day	52% 6% 15% 15% 9% 3	2252
	21st to end	Day	44% 8% 15% 20% 11% 1	2418
May	1st to 10th	Day	35% 9% 14% 23% 13% 6%	4110
	11th to 20th	Day	23% 5% 11% 24% 34% 3	4186
	21st to end	Day	28% 13% 22% 33% 5%	4814
June	1st to 10th	Day	39% 10% 15% 22% 13% 2	2660
	11th to 20th	Day	24% 8% 16% 30% 18% 4	2660
	21st to end	Day	17% 6% 15% 30% 25% 7%	2660
July	1st to 10th	Day	8% 4 7% 16% 17% 47%	4351
	11th to 20th	Day	11% 3 8% 20% 25% 33%	4133
	21st to end	Day	5% 5% 10% 28% 32% 21%	4315
August	1st to 10th	Day	10% 5% 11% 27% 35% 13%	4076
	11th to 20th	Day	12% 7% 13% 33% 26% 10%	4065
	21st to end	Day	14% 4 11% 29% 32% 9%	4255
September	1st to 10th	Day	13% 4 9% 19% 34% 22%	2280
	11th to 20th	Day	23% 6% 14% 26% 25% 5%	2180
	21st to end	Day	20% 5% 13% 23% 23% 16%	2056
October	1st to 10th	Day	18% 3 9% 18% 18% 33%	3180
	11th to 20th	Day	28% 8% 13% 28% 17% 6%	3161
	21st to end	Day	41% 7% 10% 19% 15% 8%	3448
November	1st to 10th	Day	47% 7% 12% 17% 12% 5%	1852
	11th to 20th	Day	49% 7% 14% 13% 9% 8%	1520
	21st to end	Day	48% 7% 10% 12% 13% 10%	1520
December	1st to 10th	Day	46% 6% 12% 14% 14% 8%	1520
	11th to 20th	Day	62% 8% 9% 9% 9% 3	1928
	21st to end	Day	66% 6% 6% 11% 8% 3	2794
January	1st to 10th	Night	63% 9% 12% 9% 4 2	4304
	11th to 20th	Night	64% 8% 8% 8% 6% 6%	4110
	21st to end	Night	67% 5% 6% 10% 8% 4	4521
February	1st to 10th	Night	51% 7% 12% 16% 10% 5%	2470
	11th to 20th	Night	54% 7% 11% 15% 10% 3	2404
	21st to end	Night	51% 7% 14% 17% 7% 3	1914
March	1st to 10th	Night	63% 8% 10% 15% 5%	3432
	11th to 20th	Night	39% 13% 15% 15% 11% 8%	3490
	21st to end	Night	64% 11% 11% 10% 4 1	3828
April	1st to 10th	Night	53% 11% 14% 15% 5% 2	1933
	11th to 20th	Night	49% 10% 16% 14% 7% 3	1879
	21st to end	Night	43% 11% 18% 20% 6% 2	1760
May	1st to 10th	Night	31% 13% 19% 17% 13% 7%	2860
	11th to 20th	Night	24% 7% 17% 19% 29% 5%	2717
	21st to end	Night	27% 20% 22% 27% 4	2762
June	1st to 10th	Night	39% 10% 19% 21% 10% 1	1520
	11th to 20th	Night	23% 10% 19% 28% 16% 4	1520
	21st to end	Night	15% 8% 17% 29% 24% 7%	1520
July	1st to 10th	Night	8% 6% 10% 15% 14% 47%	2500
	11th to 20th	Night	10% 4 10% 15% 32% 28%	2706
	21st to end	Night	10% 9% 12% 24% 29% 16%	3011
August	1st to 10th	Night	11% 8% 16% 27% 28% 9%	2839
	11th to 20th	Night	13% 7% 15% 31% 26% 8%	2839
	21st to end	Night	14% 5% 12% 29% 30% 11%	3420
September	1st to 10th	Night	11% 5% 11% 19% 31% 24%	1900
	11th to 20th	Night	19% 8% 18% 29% 21% 6%	1998
	21st to end	Night	23% 5% 14% 21% 19% 17%	2123
October	1st to 10th	Night	18% 4 8% 18% 19% 34%	3800
	11th to 20th	Night	34% 8% 11% 26% 16% 5%	3777
	21st to end	Night	40% 8% 11% 18% 15% 8%	4121
November	1st to 10th	Night	49% 9% 13% 13% 12% 5%	2295
	11th to 20th	Night	53% 9% 12% 12% 8% 6%	2660
	21st to end	Night	45% 7% 10% 16% 13% 9%	2660
December	1st to 10th	Night	47% 7% 11% 13% 16% 6%	2660
	11th to 20th	Night	62% 7% 7% 12% 11% 2	3276
	21st to end	Night	57% 11% 13% 12% 6% 2	4862

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	42% 15% 21% 16% 5% 1	242
	11th to 20th	Day	37% 9% 21% 20% 10% 4	370
	21st to end	Day	31% 10% 21% 24% 12% 3	407
February	1st to 10th	Day	27% 14% 26% 23% 7% 3	370
	11th to 20th	Day	37% 12% 23% 19% 8%	365
	21st to end	Day	34% 17% 25% 16% 7% 1	347
March	1st to 10th	Day	37% 17% 25% 16% 5% 1	460
	11th to 20th	Day	30% 13% 25% 21% 7% 3	460
	21st to end	Day	33% 17% 25% 17% 7%	506
April	1st to 10th	Day	31% 18% 26% 17% 6% 2	460
	11th to 20th	Day	32% 15% 22% 23% 6% 2	452
	21st to end	Day	24% 15% 31% 19% 9% 3	460
May	1st to 10th	Day	21% 17% 29% 21% 10% 2	463
	11th to 20th	Day	28% 14% 25% 21% 9% 3	488
	21st to end	Day	20% 16% 27% 24% 10% 3	529
June	1st to 10th	Day	19% 13% 27% 25% 12% 3	490
	11th to 20th	Day	12% 18% 31% 28% 9% 2	490
	21st to end	Day	5% 9% 34% 35% 14% 3	490
July	1st to 10th	Day	6% 6% 30% 39% 15% 4	486
	11th to 20th	Day	3 5% 33% 39% 16% 5%	484
	21st to end	Day	1 5% 24% 44% 20% 6%	531
August	1st to 10th	Day	3 6% 29% 37% 18% 7%	487
	11th to 20th	Day	3 8% 22% 42% 18% 7%	477
	21st to end	Day	5% 5% 24% 41% 17% 8%	539
September	1st to 10th	Day	6% 6% 26% 36% 19% 6%	490
	11th to 20th	Day	9% 11% 21% 38% 16% 4	490
	21st to end	Day	10% 9% 25% 31% 19% 5%	490
October	1st to 10th	Day	10% 11% 23% 31% 19% 6%	490
	11th to 20th	Day	16% 8% 17% 29% 22% 7%	490
	21st to end	Day	18% 11% 25% 26% 17% 3	539
November	1st to 10th	Day	23% 11% 22% 27% 12% 5%	440
	11th to 20th	Day	21% 9% 19% 23% 21% 8%	180
	21st to end	Day	22% 9% 13% 32% 21% 3	180
December	1st to 10th	Day	27% 15% 18% 19% 13% 7%	180
	11th to 20th	Day	37% 7% 17% 22% 13% 4	180
	21st to end	Day	34% 8% 21% 21% 14% 2	198
January	1st to 10th	Night	31% 7% 16% 27% 17% 3	760
	11th to 20th	Night	30% 6% 15% 28% 16% 5%	760
	21st to end	Night	32% 4 11% 29% 21% 4	836
February	1st to 10th	Night	26% 8% 14% 33% 17% 2	760
	11th to 20th	Night	28% 8% 16% 25% 19% 4	744
	21st to end	Night	28% 7% 19% 30% 15%	628
March	1st to 10th	Night	36% 10% 15% 24% 12% 3	760
	11th to 20th	Night	29% 7% 13% 26% 22% 3	760
	21st to end	Night	31% 10% 16% 27% 14% 2	836
April	1st to 10th	Night	27% 8% 18% 28% 17% 3	760
	11th to 20th	Night	23% 9% 19% 26% 19% 4	751
	21st to end	Night	22% 6% 13% 32% 21% 5%	620
May	1st to 10th	Night	16% 8% 17% 30% 24% 5%	570
	11th to 20th	Night	17% 7% 10% 30% 28% 7%	496
	21st to end	Night	17% 8% 15% 32% 25% 4	411
June	1st to 10th	Night	17% 7% 12% 33% 28% 3	380
	11th to 20th	Night	8% 5% 18% 46% 22% 2	380
	21st to end	Night	7% 4 8% 39% 40% 2	380
July	1st to 10th	Night	4 3 9% 37% 43% 4	370
	11th to 20th	Night	3 5% 3 34% 46% 9%	491
	21st to end	Night	2 3 6% 26% 49% 15%	624
August	1st to 10th	Night	2 4 7% 27% 47% 12%	567
	11th to 20th	Night	3 2 7% 24% 52% 12%	564
	21st to end	Night	4 3 8% 31% 43% 12%	784
September	1st to 10th	Night	4 1 9% 30% 44% 12%	760
	11th to 20th	Night	6% 4 10% 31% 38% 11%	760
	21st to end	Night	9% 4 11% 28% 36% 12%	760
October	1st to 10th	Night	9% 4 11% 30% 37% 9%	760
	11th to 20th	Night	15% 4 10% 28% 32% 11%	760
	21st to end	Night	16% 6% 12% 30% 27% 9%	836
November	1st to 10th	Night	23% 6% 16% 28% 20% 7%	754
	11th to 20th	Night	25% 8% 13% 31% 21% 4	760
	21st to end	Night	23% 5% 15% 32% 21% 3	760
December	1st to 10th	Night	26% 8% 14% 29% 20% 3	760
	11th to 20th	Night	33% 8% 17% 26% 14% 3	760
	21st to end	Night	39% 7% 14% 25% 12% 2	836

Page generated at 2024-11-01 19:47:44. Version ac07

Copyright © 2024 Attilla Danko.