Erwin W. Fick Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Erwin W. Fick Observatory clear sky chart from 2005-11-06 to 2024-02-10.

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	13% 8% 3 7% 6% 3 5% 5% 5% 7% 38%	78332
	Night	12% 8% 3 7% 5% 3 4 4 5% 7% 41%	80684
Transparency	Day	44% 7% 13% 22% 12% 1	78044
	Night	43% 6% 13% 23% 14% 2	80492
Seeing	Day	15% 10% 29% 28% 14% 3	14765
	Night	15% 9% 33% 32% 11% 1	24824

By Month

Percentage Cloud Cover SE (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	8% 12% 6% 17% 13% 4 5% 4 5% 5% 21%	2536
	11th to 20th	Day	8% 13% 6% 10% 8% 5% 8% 6% 6% 7% 23%	2850
	21st to end	Day	13% 15% 8% 14% 8% 3 5% 4 4 5% 19%	3135
February	1st to 10th	Day	10% 14% 5% 8% 7% 4 6% 5% 5% 7% 28%	1701
	11th to 20th	Day	11% 10% 4 8% 6% 3 6% 5% 5% 6% 36%	1574
	21st to end	Day	15% 11% 4 9% 7% 4 5% 4 4 5% 33%	1425
March	1st to 10th	Day	14% 10% 5% 7% 5% 3 5% 5% 4 6% 34%	1980
	11th to 20th	Day	14% 9% 5% 8% 6% 3 3 5% 5% 8% 33%	1980
	21st to end	Day	20% 13% 4 7% 5% 3 5% 4 4 6% 29%	2178
April	1st to 10th	Day	18% 11% 3 6% 5% 3 4 5% 6% 6% 35%	2135
	11th to 20th	Day	18% 9% 3 7% 5% 3 4 4 5% 6% 35%	2134
	21st to end	Day	22% 7% 3 6% 4 3 4 4 5% 6% 35%	2317
May	1st to 10th	Day	19% 8% 3 5% 5% 3 5% 5% 6% 7% 33%	2340
	11th to 20th	Day	17% 7% 3 6% 6% 3 4 6% 6% 7% 37%	2420
	21st to end	Day	16% 7% 3 6% 7% 3 5% 4 5% 7% 36%	2725
June	1st to 10th	Day	11% 5% 2 5% 5% 3 5% 5% 6% 8% 45%	2520
	11th to 20th	Day	10% 4 2 5% 5% 3 4 6% 7% 10% 45%	2520
	21st to end	Day	9% 5% 2 5% 6% 3 7% 5% 6% 9% 42%	2520
July	1st to 10th	Day	7% 5% 2 4 4 2 4 5% 7% 11% 48%	2520
	11th to 20th	Day	6% 3 2 4 4 4 5% 6% 7% 8% 51%	2482
	21st to end	Day	6% 4 2 4 6% 3 5% 6% 7% 10% 48%	2546
August	1st to 10th	Day	9% 5% 3 6% 6% 4 5% 5% 7% 9% 42%	2328
	11th to 20th	Day	11% 5% 2 5% 5% 3 4 5% 7% 8% 45%	2301
	21st to end	Day	9% 4 2 5% 5% 3 4 5% 5% 7% 51%	2444
September	1st to 10th	Day	12% 5% 2 4 4 2 4 4 5% 7% 52%	2160
	11th to 20th	Day	10% 5% 2 4 5% 3 5% 5% 6% 8% 49%	2077
	21st to end	Day	12% 5% 2 4 3 3 4 4 5% 6% 50%	1926
October	1st to 10th	Day	16% 6% 3 5% 5% 2 3 4 4 7% 46%	1800
	11th to 20th	Day	16% 7% 3 5% 5% 2 4 4 4 6% 45%	1800
	21st to end	Day	15% 9% 3 5% 5% 3 4 4 5% 6% 41%	1980
November	1st to 10th	Day	10% 7% 3 4 5% 2 5% 4 6% 8% 46%	1717
	11th to 20th	Day	13% 8% 3 6% 6% 3 3 5% 5% 7% 40%	1520
	21st to end	Day	15% 9% 4 6% 5% 3 5% 3 5% 6% 41%	1520
December	1st to 10th	Day	12% 9% 4 9% 5% 3 5% 5% 5% 8% 35%	1520
	11th to 20th	Day	11% 9% 4 8% 7% 4 5% 4 5% 8% 32%	1918
	21st to end	Day	21% 14% 6% 13% 7% 3 4 3 4 5% 19%	2783
January	1st to 10th	Night	10% 11% 6% 20% 10% 4 4 4 4 5% 24%	4414
	11th to 20th	Night	9% 13% 5% 9% 7% 3 7% 5% 9% 6% 26%	4120
	21st to end	Night	14% 14% 6% 12% 7% 3 5% 5% 4 6% 24%	4532
February	1st to 10th	Night	11% 11% 5% 10% 7% 3 5% 4 5% 6% 32%	2464
	11th to 20th	Night	11% 9% 4 6% 5% 4 5% 5% 5% 6% 39%	2273
	21st to end	Night	12% 8% 4 8% 6% 3 4 3 4 6% 41%	1844
March	1st to 10th	Night	13% 9% 3 7% 4 3 3 3 6% 7% 43%	1980
	11th to 20th	Night	14% 8% 4 6% 6% 3 4 4 5% 7% 39%	1980
	21st to end	Night	19% 11% 4 9% 6% 3 5% 4 4 6% 29%	2178
April	1st to 10th	Night	14% 9% 2 5% 6% 3 4 5% 4 7% 42%	1824
	11th to 20th	Night	16% 8% 3 6% 5% 3 4 4 5% 5% 40%	1775
	21st to end	Night	16% 7% 3 6% 5% 3 4 4 4 6% 41%	1639
May	1st to 10th	Night	17% 5% 2 5% 4 3 5% 5% 7% 8% 40%	1620
	11th to 20th	Night	15% 6% 3 5% 4 3 4 4 6% 9% 41%	1471
	21st to end	Night	13% 6% 2 6% 5% 3 5% 5% 5% 8% 42%	1551
June	1st to 10th	Night	6% 3 2 5% 5% 3 5% 6% 5% 8% 52%	1440
	11th to 20th	Night	7% 5% 2 5% 4 2 4 6% 5% 9% 51%	1440
	21st to end	Night	8% 4 2 4 4 2 4 5% 6% 9% 52%	1440
July	1st to 10th	Night	5% 3 1 3 4 3 3 5% 6% 9% 59%	1440
	11th to 20th	Night	4 3 1 3 3 3 4 4 6% 9% 62%	1475
	21st to end	Night	4 2 1 3 4 3 5% 5% 7% 9% 56%	1772
August	1st to 10th	Night	7% 5% 2 5% 6% 3 4 4 6% 7% 50%	1611
	11th to 20th	Night	7% 3 2 4 4 3 4 4 5% 7% 57%	1600
	21st to end	Night	8% 4 1 4 4 2 3 4 5% 7% 57%	1911
September	1st to 10th	Night	11% 3 2 5% 4 2 3 3 4 5% 57%	1800
	11th to 20th	Night	10% 5% 2 4 3 3 3 3 5% 6% 56%	1880
	21st to end	Night	9% 4 2 4 3 2 4 4 5% 7% 58%	2016
October	1st to 10th	Night	13% 6% 2 4 4 2 4 3 4 5% 52%	2160
	11th to 20th	Night	16% 5% 2 4 5% 2 3 3 4 6% 48%	2160
	21st to end	Night	15% 9% 3 4 4 2 3 3 4 6% 46%	2376
November	1st to 10th	Night	10% 5% 2 4 3 2 4 4 4 7% 53%	2355
	11th to 20th	Night	12% 7% 3 6% 5% 2 4 4 5% 6% 45%	2660
	21st to end	Night	14% 7% 4 7% 4 3 4 4 4 7% 44%	2660
December	1st to 10th	Night	10% 10% 4 8% 6% 4 5% 5% 6% 6% 36%	2660
	11th to 20th	Night	11% 10% 4 8% 6% 3 4 5% 5% 6% 39%	3279
	21st to end	Night	19% 14% 7% 13% 6% 2 4 4 3 4 23%	4884

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	63% 8% 11% 12% 7%	2537
	11th to 20th	Day	59% 4 10% 21% 5%	2850
	21st to end	Day	66% 6% 10% 14% 4	3135
February	1st to 10th	Day	55% 5% 13% 18% 9% 1	1701
	11th to 20th	Day	49% 6% 12% 20% 11% 2	1583
	21st to end	Day	53% 4 14% 17% 10% 2	1425
March	1st to 10th	Day	50% 5% 15% 21% 8% 1	1980
	11th to 20th	Day	50% 6% 13% 21% 10% 1	1980
	21st to end	Day	58% 5% 12% 17% 6% 2	2178
April	1st to 10th	Day	48% 6% 11% 23% 10% 1	2135
	11th to 20th	Day	49% 6% 11% 21% 12% 1	2134
	21st to end	Day	48% 6% 11% 23% 12% 1	2317
May	1st to 10th	Day	49% 8% 12% 19% 11% 1	2340
	11th to 20th	Day	46% 8% 12% 22% 11% 1	2424
	21st to end	Day	46% 8% 13% 19% 12% 2	2725
June	1st to 10th	Day	35% 9% 16% 23% 16% 1	2520
	11th to 20th	Day	32% 7% 15% 24% 19% 2	2520
	21st to end	Day	36% 9% 14% 24% 14% 2	2520
July	1st to 10th	Day	28% 8% 16% 31% 13% 4	2451
	11th to 20th	Day	29% 8% 16% 26% 18% 3	2407
	21st to end	Day	29% 8% 17% 28% 16% 2	2405
August	1st to 10th	Day	36% 11% 16% 25% 12% 2	2314
	11th to 20th	Day	35% 8% 14% 28% 15% 1	2301
	21st to end	Day	32% 7% 12% 27% 19% 4	2444
September	1st to 10th	Day	32% 6% 14% 26% 19% 4	2160
	11th to 20th	Day	32% 6% 14% 30% 18% 1	2077
	21st to end	Day	33% 5% 11% 30% 19% 1	1926
October	1st to 10th	Day	38% 5% 12% 26% 17% 1	1800
	11th to 20th	Day	40% 6% 8% 24% 19% 3	1800
	21st to end	Day	44% 5% 12% 22% 16% 2	1980
November	1st to 10th	Day	35% 6% 16% 22% 18% 2	1717
	11th to 20th	Day	43% 5% 14% 22% 16% 1	1520
	21st to end	Day	45% 5% 14% 24% 11% 1	1520
December	1st to 10th	Day	48% 6% 18% 18% 9% 2	1520
	11th to 20th	Day	49% 6% 18% 21% 6%	1915
	21st to end	Day	68% 5% 10% 13% 4 1	2783
January	1st to 10th	Night	62% 6% 10% 13% 9%	4414
	11th to 20th	Night	55% 5% 14% 15% 10% 1	4120
	21st to end	Night	61% 6% 12% 14% 7% 1	4532
February	1st to 10th	Night	52% 5% 12% 20% 10% 2	2464
	11th to 20th	Night	45% 6% 12% 23% 12% 2	2274
	21st to end	Night	46% 5% 11% 20% 16% 3	1844
March	1st to 10th	Night	41% 5% 14% 28% 11% 1	1980
	11th to 20th	Night	45% 6% 12% 22% 14% 2	1980
	21st to end	Night	56% 6% 13% 16% 8% 1	2178
April	1st to 10th	Night	42% 6% 12% 24% 14% 2	1824
	11th to 20th	Night	45% 6% 10% 21% 16% 2	1775
	21st to end	Night	43% 6% 13% 23% 14% 2	1639
May	1st to 10th	Night	41% 7% 16% 21% 13% 1	1620
	11th to 20th	Night	40% 7% 14% 26% 13% 1	1472
	21st to end	Night	39% 8% 14% 23% 12% 4	1552
June	1st to 10th	Night	30% 7% 16% 29% 16% 3	1440
	11th to 20th	Night	29% 8% 13% 22% 22% 5%	1440
	21st to end	Night	29% 7% 15% 28% 18% 3	1440
July	1st to 10th	Night	21% 8% 17% 33% 18% 3	1400
	11th to 20th	Night	19% 5% 19% 35% 17% 4	1427
	21st to end	Night	21% 8% 18% 31% 20% 3	1673
August	1st to 10th	Night	31% 8% 15% 28% 15% 3	1601
	11th to 20th	Night	27% 7% 13% 33% 18% 3	1600
	21st to end	Night	26% 7% 13% 27% 21% 7%	1911
September	1st to 10th	Night	29% 5% 12% 25% 25% 5%	1800
	11th to 20th	Night	29% 5% 11% 34% 20% 1	1880
	21st to end	Night	26% 5% 10% 32% 24% 2	2016
October	1st to 10th	Night	34% 5% 10% 27% 20% 3	2160
	11th to 20th	Night	37% 5% 11% 24% 19% 5%	2160
	21st to end	Night	40% 5% 12% 22% 20% 2	2376
November	1st to 10th	Night	31% 5% 16% 25% 20% 4	2355
	11th to 20th	Night	40% 5% 14% 26% 14% 1	2660
	21st to end	Night	42% 4 12% 26% 14% 2	2660
December	1st to 10th	Night	48% 5% 14% 23% 10% 1	2660
	11th to 20th	Night	44% 6% 14% 28% 7%	3281
	21st to end	Night	65% 6% 8% 15% 6%	4884

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	19% 12% 34% 24% 9% 2	270
	11th to 20th	Day	18% 12% 43% 22% 4	270
	21st to end	Day	19% 12% 35% 27% 6% 1	297
February	1st to 10th	Day	16% 18% 40% 21% 3 1	267
	11th to 20th	Day	18% 18% 38% 20% 5% 1	240
	21st to end	Day	22% 17% 42% 17% 3	198
March	1st to 10th	Day	17% 17% 40% 19% 8%	240
	11th to 20th	Day	28% 10% 34% 19% 9%	240
	21st to end	Day	34% 16% 29% 16% 5%	264
April	1st to 10th	Day	26% 13% 34% 21% 6%	395
	11th to 20th	Day	24% 15% 29% 22% 10%	412
	21st to end	Day	24% 14% 31% 22% 8% 2	577
May	1st to 10th	Day	22% 13% 33% 22% 8% 1	603
	11th to 20th	Day	23% 13% 29% 23% 10% 3	625
	21st to end	Day	17% 9% 25% 30% 15% 4	679
June	1st to 10th	Day	8% 6% 27% 29% 25% 4	630
	11th to 20th	Day	10% 6% 28% 37% 15% 4	630
	21st to end	Day	8% 6% 36% 33% 14% 3	630
July	1st to 10th	Day	7% 4 17% 34% 25% 12%	621
	11th to 20th	Day	6% 4 25% 34% 22% 8%	618
	21st to end	Day	6% 1 21% 41% 26% 5%	684
August	1st to 10th	Day	9% 4 19% 35% 27% 6%	626
	11th to 20th	Day	13% 2 17% 36% 24% 7%	615
	21st to end	Day	10% 4 20% 37% 23% 6%	563
September	1st to 10th	Day	13% 5% 24% 31% 21% 6%	450
	11th to 20th	Day	7% 4 25% 37% 20% 5%	367
	21st to end	Day	13% 9% 26% 33% 15% 3	270
October	1st to 10th	Day	19% 6% 28% 30% 13% 3	270
	11th to 20th	Day	19% 21% 33% 19% 7% 1	270
	21st to end	Day	20% 15% 34% 21% 7% 2	297
November	1st to 10th	Day	14% 13% 41% 20% 8% 3	270
	11th to 20th	Day	17% 21% 33% 20% 8% 1	270
	21st to end	Day	23% 13% 37% 20% 5% 1	270
December	1st to 10th	Day	10% 13% 45% 22% 8% 1	270
	11th to 20th	Day	13% 16% 36% 26% 9% 1	270
	21st to end	Day	24% 16% 40% 17% 3	297
January	1st to 10th	Night	12% 14% 37% 30% 7%	950
	11th to 20th	Night	16% 13% 35% 27% 8% 1	950
	21st to end	Night	19% 11% 34% 29% 6%	1045
February	1st to 10th	Night	17% 11% 38% 30% 4	948
	11th to 20th	Night	16% 13% 39% 27% 5%	879
	21st to end	Night	16% 12% 42% 23% 5% 2	660
March	1st to 10th	Night	19% 11% 36% 25% 9% 1	540
	11th to 20th	Night	19% 9% 37% 27% 9%	540
	21st to end	Night	22% 12% 38% 21% 6% 1	594
April	1st to 10th	Night	16% 15% 40% 26% 4	540
	11th to 20th	Night	18% 13% 35% 29% 5% 1	533
	21st to end	Night	20% 8% 36% 27% 7% 1	540
May	1st to 10th	Night	19% 8% 34% 31% 8%	540
	11th to 20th	Night	17% 9% 31% 31% 11% 1	531
	21st to end	Night	16% 6% 28% 35% 14%	584
June	1st to 10th	Night	8% 5% 26% 41% 19%	540
	11th to 20th	Night	9% 4 29% 47% 11%	540
	21st to end	Night	8% 5% 31% 42% 13% 1	540
July	1st to 10th	Night	6% 1 15% 44% 31% 2	525
	11th to 20th	Night	4 2 22% 45% 25% 2	522
	21st to end	Night	4 3 17% 51% 25% 1	591
August	1st to 10th	Night	8% 2 16% 48% 24% 1	537
	11th to 20th	Night	8% 2 16% 43% 27% 3	534
	21st to end	Night	8% 3 21% 43% 22% 3	594
September	1st to 10th	Night	10% 4 24% 39% 21% 2	540
	11th to 20th	Night	13% 1 25% 39% 20% 2	540
	21st to end	Night	10% 7% 30% 38% 15% 1	576
October	1st to 10th	Night	15% 7% 33% 31% 12% 1	720
	11th to 20th	Night	18% 13% 34% 28% 8%	720
	21st to end	Night	23% 9% 32% 28% 8%	792
November	1st to 10th	Night	14% 9% 39% 30% 9%	794
	11th to 20th	Night	16% 14% 42% 22% 6%	950
	21st to end	Night	17% 13% 34% 30% 7%	950
December	1st to 10th	Night	15% 11% 39% 28% 7%	950
	11th to 20th	Night	19% 9% 34% 32% 5% 1	950
	21st to end	Night	21% 13% 38% 24% 4	1045

Page generated at 2024-02-07 05:11:53. Version ac07

Copyright 2024 Attilla Danko