Yarger Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Yarger Observatory clear sky chart from 2005-11-06 to 2024-03-28.

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% 10% 4 7% 6% 4 5% 5% 5% 7% 32%	78704
	Night	16% 11% 5% 8% 6% 3 4 5% 5% 7% 31%	81341
Transparency	Day	52% 3 11% 21% 12% 1	78407
	Night	54% 3 10% 20% 12% 1	81159
Seeing	Day	17% 10% 27% 24% 15% 6%	14812
	Night	19% 8% 28% 30% 13% 1	24856

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	15% 20% 8% 10% 7% 4 6% 5% 4 5% 16%	2527
	11th to 20th	Day	15% 16% 8% 12% 10% 5% 8% 8% 5% 4 9%	2530
	21st to end	Day	25% 22% 9% 12% 6% 3 4 3 3 4 10%	2791
February	1st to 10th	Day	14% 13% 8% 11% 11% 6% 6% 4 4 5% 18%	1807
	11th to 20th	Day	15% 11% 6% 14% 9% 4 5% 5% 5% 5% 22%	1848
	21st to end	Day	16% 14% 8% 11% 7% 4 5% 4 4 6% 21%	1570
March	1st to 10th	Day	15% 11% 5% 8% 7% 4 5% 5% 4 7% 28%	1900
	11th to 20th	Day	13% 10% 5% 8% 7% 4 5% 5% 6% 7% 31%	2028
	21st to end	Day	19% 13% 5% 7% 7% 4 5% 5% 4 6% 25%	2332
April	1st to 10th	Day	18% 11% 5% 7% 5% 4 4 4 5% 7% 30%	2160
	11th to 20th	Day	16% 11% 2 6% 5% 3 4 5% 5% 6% 36%	2165
	21st to end	Day	18% 9% 3 6% 5% 3 5% 3 5% 7% 35%	2340
May	1st to 10th	Day	18% 8% 3 8% 5% 4 5% 5% 6% 8% 31%	2340
	11th to 20th	Day	20% 8% 2 5% 4 3 4 5% 5% 7% 37%	2301
	21st to end	Day	11% 6% 3 6% 6% 3 5% 5% 6% 9% 40%	2676
June	1st to 10th	Day	9% 5% 2 6% 5% 3 5% 5% 6% 9% 44%	2520
	11th to 20th	Day	10% 4 2 5% 5% 3 5% 6% 6% 9% 44%	2520
	21st to end	Day	10% 5% 3 6% 5% 4 6% 5% 7% 9% 41%	2520
July	1st to 10th	Day	6% 5% 3 5% 5% 3 5% 6% 6% 10% 46%	2520
	11th to 20th	Day	8% 5% 2 5% 5% 3 6% 5% 6% 10% 46%	2520
	21st to end	Day	7% 4 3 5% 4 3 6% 6% 7% 9% 45%	2733
August	1st to 10th	Day	7% 4 2 5% 5% 4 6% 6% 7% 10% 44%	2327
	11th to 20th	Day	9% 5% 2 6% 6% 3 6% 6% 6% 8% 43%	2303
	21st to end	Day	9% 5% 3 5% 5% 2 5% 5% 6% 9% 47%	2376
September	1st to 10th	Day	11% 6% 2 5% 5% 3 4 5% 5% 9% 45%	2128
	11th to 20th	Day	12% 4 2 4 5% 3 5% 5% 6% 8% 46%	1980
	21st to end	Day	12% 6% 3 5% 6% 4 4 4 6% 8% 41%	1980
October	1st to 10th	Day	13% 6% 3 7% 6% 4 4 5% 5% 6% 42%	1980
	11th to 20th	Day	19% 8% 3 7% 6% 4 5% 5% 5% 8% 31%	1782
	21st to end	Day	22% 10% 4 7% 7% 4 5% 4 5% 6% 26%	1782
November	1st to 10th	Day	12% 10% 4 5% 5% 3 4 4 6% 7% 38%	1672
	11th to 20th	Day	16% 16% 6% 7% 7% 4 5% 4 5% 6% 24%	1710
	21st to end	Day	21% 14% 6% 9% 6% 3 4 4 4 5% 23%	1710
December	1st to 10th	Day	15% 17% 10% 10% 8% 3 4 4 4 5% 22%	1625
	11th to 20th	Day	13% 19% 9% 12% 8% 3 4 4 4 6% 17%	1918
	21st to end	Day	22% 20% 8% 12% 8% 3 4 4 4 4 11%	2783
January	1st to 10th	Night	16% 17% 9% 11% 9% 4 5% 4 5% 5% 16%	4428
	11th to 20th	Night	15% 18% 10% 15% 8% 3 5% 7% 5% 4 11%	4440
	21st to end	Night	26% 17% 9% 12% 7% 3 3 4 3 4 11%	4875
February	1st to 10th	Night	17% 14% 6% 11% 9% 4 5% 4 5% 6% 21%	2371
	11th to 20th	Night	14% 11% 6% 11% 8% 5% 4 4 5% 6% 25%	2218
	21st to end	Night	19% 12% 5% 10% 6% 3 4 5% 5% 5% 26%	1884
March	1st to 10th	Night	15% 10% 5% 9% 6% 3 4 5% 3 6% 33%	2280
	11th to 20th	Night	14% 8% 3 6% 5% 4 4 5% 5% 7% 39%	2150
	21st to end	Night	21% 9% 4 7% 5% 3 4 4 4 7% 32%	2193
April	1st to 10th	Night	15% 9% 3 6% 6% 3 5% 5% 5% 8% 36%	1800
	11th to 20th	Night	19% 8% 3 6% 5% 3 5% 5% 5% 6% 37%	1742
	21st to end	Night	19% 8% 2 6% 5% 2 5% 4 5% 7% 36%	1620
May	1st to 10th	Night	16% 9% 3 7% 6% 4 5% 6% 6% 7% 33%	1620
	11th to 20th	Night	19% 8% 3 5% 4 3 4 4 4 7% 39%	1592
	21st to end	Night	11% 5% 2 6% 5% 3 5% 6% 6% 9% 42%	1597
June	1st to 10th	Night	9% 4 2 4 4 4 5% 4 7% 11% 47%	1440
	11th to 20th	Night	9% 5% 2 6% 5% 3 5% 6% 6% 10% 44%	1440
	21st to end	Night	9% 5% 2 4 6% 3 4 5% 7% 11% 43%	1440
July	1st to 10th	Night	6% 4 2 4 4 2 4 6% 6% 10% 51%	1440
	11th to 20th	Night	8% 3 1 4 4 2 5% 3 5% 10% 52%	1440
	21st to end	Night	5% 5% 1 4 5% 3 5% 5% 6% 9% 52%	1583
August	1st to 10th	Night	7% 4 1 4 4 3 4 5% 7% 11% 49%	1611
	11th to 20th	Night	8% 4 2 5% 5% 4 5% 5% 6% 9% 48%	1598
	21st to end	Night	9% 4 2 4 5% 3 4 5% 5% 8% 51%	1977
September	1st to 10th	Night	10% 6% 3 5% 4 3 4 5% 5% 7% 48%	1813
	11th to 20th	Night	11% 4 2 4 6% 2 4 4 4 7% 53%	1980
	21st to end	Night	13% 6% 2 5% 5% 3 4 5% 5% 8% 44%	1980
October	1st to 10th	Night	14% 7% 2 5% 5% 2 4 4 5% 6% 46%	1980
	11th to 20th	Night	18% 9% 3 8% 6% 3 4 3 4 6% 37%	2176
	21st to end	Night	23% 11% 3 6% 5% 3 4 4 4 5% 32%	2574
November	1st to 10th	Night	14% 9% 3 7% 5% 3 4 4 5% 6% 39%	2406
	11th to 20th	Night	15% 13% 5% 8% 7% 3 4 6% 6% 6% 27%	2470
	21st to end	Night	17% 16% 6% 8% 5% 3 4 3 5% 6% 26%	2470
December	1st to 10th	Night	16% 18% 8% 10% 8% 3 4 4 4 6% 18%	2550
	11th to 20th	Night	16% 16% 9% 11% 8% 4 5% 5% 4 4 18%	3279
	21st to end	Night	27% 19% 7% 9% 6% 3 4 4 4 5% 12%	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	71% 2 10% 15% 3	2528
	11th to 20th	Day	76% 1 8% 10% 5%	2530
	21st to end	Day	81% 1 6% 9% 3	2791
February	1st to 10th	Day	68% 2 8% 14% 6% 1	1807
	11th to 20th	Day	64% 3 8% 16% 9% 1	1858
	21st to end	Day	64% 2 10% 15% 7% 1	1570
March	1st to 10th	Day	56% 3 11% 20% 9%	1900
	11th to 20th	Day	52% 3 12% 21% 12% 1	2028
	21st to end	Day	62% 2 9% 20% 5% 1	2332
April	1st to 10th	Day	55% 3 9% 21% 12%	2160
	11th to 20th	Day	50% 3 10% 22% 13% 3	2165
	21st to end	Day	50% 2 12% 19% 14% 2	2340
May	1st to 10th	Day	51% 3 12% 22% 10% 1	2340
	11th to 20th	Day	49% 3 9% 23% 14% 2	2305
	21st to end	Day	41% 4 13% 26% 14% 2	2676
June	1st to 10th	Day	38% 3 12% 28% 18% 1	2520
	11th to 20th	Day	37% 4 10% 26% 19% 3	2520
	21st to end	Day	40% 4 14% 23% 16% 3	2520
July	1st to 10th	Day	35% 4 11% 26% 20% 4	2451
	11th to 20th	Day	35% 3 11% 30% 17% 3	2445
	21st to end	Day	34% 4 13% 29% 18% 2	2581
August	1st to 10th	Day	34% 4 16% 29% 16% 2	2314
	11th to 20th	Day	38% 4 13% 28% 16% 1	2303
	21st to end	Day	35% 3 11% 27% 20% 4	2376
September	1st to 10th	Day	38% 3 15% 24% 17% 3	2128
	11th to 20th	Day	36% 3 10% 31% 19% 1	1980
	21st to end	Day	41% 3 9% 27% 19% 1	1980
October	1st to 10th	Day	43% 3 11% 26% 15% 2	1980
	11th to 20th	Day	53% 2 10% 22% 13%	1782
	21st to end	Day	59% 2 10% 18% 9% 1	1782
November	1st to 10th	Day	45% 3 12% 24% 16% 1	1672
	11th to 20th	Day	61% 1 10% 19% 7% 1	1710
	21st to end	Day	64% 2 11% 17% 5%	1710
December	1st to 10th	Day	66% 2 10% 17% 5%	1625
	11th to 20th	Day	70% 2 11% 14% 3	1915
	21st to end	Day	80% 2 7% 8% 3	2783
January	1st to 10th	Night	71% 1 8% 14% 5%	4428
	11th to 20th	Night	76% 2 9% 10% 3	4440
	21st to end	Night	78% 1 7% 10% 3	4875
February	1st to 10th	Night	66% 2 10% 14% 7% 1	2371
	11th to 20th	Night	61% 2 8% 20% 9%	2219
	21st to end	Night	61% 3 10% 18% 7% 2	1884
March	1st to 10th	Night	55% 2 11% 21% 10% 1	2280
	11th to 20th	Night	46% 3 12% 22% 15% 2	2150
	21st to end	Night	55% 2 9% 23% 10% 1	2193
April	1st to 10th	Night	48% 3 11% 23% 14% 1	1800
	11th to 20th	Night	50% 2 7% 19% 19% 3	1742
	21st to end	Night	49% 2 9% 22% 15% 2	1620
May	1st to 10th	Night	50% 3 11% 22% 12% 2	1620
	11th to 20th	Night	46% 3 10% 22% 18% 1	1593
	21st to end	Night	39% 4 15% 25% 15% 2	1598
June	1st to 10th	Night	34% 3 11% 30% 19% 3	1440
	11th to 20th	Night	36% 4 13% 25% 20% 2	1440
	21st to end	Night	36% 3 17% 25% 16% 3	1440
July	1st to 10th	Night	31% 3 15% 28% 19% 5%	1400
	11th to 20th	Night	30% 4 13% 28% 22% 4	1392
	21st to end	Night	30% 5% 15% 25% 21% 5%	1495
August	1st to 10th	Night	30% 3 13% 32% 20% 2	1600
	11th to 20th	Night	33% 5% 14% 26% 20% 2	1598
	21st to end	Night	32% 4 9% 27% 24% 5%	1977
September	1st to 10th	Night	36% 3 11% 25% 21% 4	1813
	11th to 20th	Night	32% 2 7% 34% 24% 1	1980
	21st to end	Night	40% 3 8% 30% 19% 2	1980
October	1st to 10th	Night	40% 3 8% 28% 19% 1	1980
	11th to 20th	Night	50% 2 8% 25% 14% 1	2176
	21st to end	Night	56% 2 8% 21% 11% 1	2574
November	1st to 10th	Night	47% 3 9% 24% 16% 1	2406
	11th to 20th	Night	56% 3 12% 19% 8% 1	2470
	21st to end	Night	61% 2 12% 19% 6%	2470
December	1st to 10th	Night	68% 2 9% 15% 6%	2550
	11th to 20th	Night	69% 2 10% 14% 5% 1	3281
	21st to end	Night	77% 2 10% 8% 3	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	21% 17% 31% 20% 9% 1	270
	11th to 20th	Day	21% 15% 39% 17% 6% 1	270
	21st to end	Day	25% 17% 28% 25% 5%	297
February	1st to 10th	Day	23% 18% 31% 20% 7% 1	270
	11th to 20th	Day	24% 19% 33% 20% 4	270
	21st to end	Day	24% 20% 40% 11% 4	225
March	1st to 10th	Day	19% 20% 42% 14% 5%	270
	11th to 20th	Day	22% 16% 30% 24% 8% 1	398
	21st to end	Day	31% 12% 29% 19% 7% 1	490
April	1st to 10th	Day	25% 10% 31% 25% 8% 1	420
	11th to 20th	Day	24% 15% 30% 18% 11% 3	412
	21st to end	Day	24% 11% 31% 20% 11% 2	420
May	1st to 10th	Day	25% 10% 28% 22% 11% 3	423
	11th to 20th	Day	25% 9% 24% 22% 14% 5%	447
	21st to end	Day	13% 7% 26% 25% 20% 9%	630
June	1st to 10th	Day	11% 5% 27% 33% 19% 6%	630
	11th to 20th	Day	12% 5% 28% 28% 19% 7%	630
	21st to end	Day	12% 7% 28% 28% 19% 6%	630
July	1st to 10th	Day	8% 3 20% 28% 24% 16%	621
	11th to 20th	Day	11% 3 24% 27% 24% 11%	618
	21st to end	Day	6% 4 21% 34% 24% 10%	674
August	1st to 10th	Day	7% 3 16% 28% 26% 20%	446
	11th to 20th	Day	10% 4 18% 27% 29% 12%	439
	21st to end	Day	11% 3 20% 28% 26% 12%	495
September	1st to 10th	Day	15% 5% 17% 28% 24% 11%	450
	11th to 20th	Day	10% 3 20% 22% 29% 17%	450
	21st to end	Day	14% 10% 23% 24% 20% 9%	450
October	1st to 10th	Day	15% 7% 27% 25% 18% 7%	450
	11th to 20th	Day	22% 18% 24% 28% 8% 1	373
	21st to end	Day	26% 16% 38% 14% 4 2	297
November	1st to 10th	Day	16% 14% 32% 25% 9% 4	270
	11th to 20th	Day	23% 19% 31% 17% 9% 1	270
	21st to end	Day	29% 11% 38% 17% 4	270
December	1st to 10th	Day	22% 23% 32% 13% 9% 1	270
	11th to 20th	Day	21% 16% 40% 18% 4	270
	21st to end	Day	22% 22% 35% 18% 3	297
January	1st to 10th	Night	22% 14% 34% 23% 6%	950
	11th to 20th	Night	25% 13% 34% 23% 5% 1	950
	21st to end	Night	21% 10% 37% 27% 4	1036
February	1st to 10th	Night	26% 9% 36% 25% 4	760
	11th to 20th	Night	20% 13% 35% 27% 4	743
	21st to end	Night	26% 11% 36% 24% 4	628
March	1st to 10th	Night	20% 11% 35% 26% 7% 1	760
	11th to 20th	Night	18% 10% 37% 27% 7% 1	760
	21st to end	Night	24% 11% 29% 30% 6% 1	758
April	1st to 10th	Night	18% 12% 33% 30% 6% 1	540
	11th to 20th	Night	22% 9% 34% 29% 6% 1	533
	21st to end	Night	22% 6% 34% 27% 10%	540
May	1st to 10th	Night	19% 6% 32% 33% 9% 1	540
	11th to 20th	Night	24% 5% 25% 31% 15%	531
	21st to end	Night	14% 3 23% 37% 21% 1	584
June	1st to 10th	Night	10% 2 24% 45% 18% 1	540
	11th to 20th	Night	12% 3 24% 41% 19% 1	540
	21st to end	Night	11% 1 21% 41% 24% 1	540
July	1st to 10th	Night	8% 2 17% 40% 28% 5%	525
	11th to 20th	Night	9% 3 15% 42% 28% 4	522
	21st to end	Night	7% 2 15% 42% 33% 2	591
August	1st to 10th	Night	9% 2 9% 47% 29% 4	537
	11th to 20th	Night	7% 2 15% 40% 30% 5%	534
	21st to end	Night	11% 1 16% 35% 33% 5%	594
September	1st to 10th	Night	12% 3 15% 38% 28% 4	553
	11th to 20th	Night	11% 3 16% 36% 30% 5%	720
	21st to end	Night	18% 5% 23% 28% 22% 5%	720
October	1st to 10th	Night	17% 5% 24% 34% 19% 2	720
	11th to 20th	Night	23% 11% 28% 30% 8% 1	720
	21st to end	Night	28% 12% 31% 22% 7%	792
November	1st to 10th	Night	20% 9% 32% 27% 11% 1	740
	11th to 20th	Night	24% 13% 32% 24% 6% 1	760
	21st to end	Night	24% 10% 33% 28% 5%	760
December	1st to 10th	Night	25% 14% 35% 22% 5%	840
	11th to 20th	Night	24% 11% 36% 24% 4	950
	21st to end	Night	31% 13% 32% 22% 2	1045

Page generated at 2024-03-24 23:37:05. Version ac07

Copyright © 2024 Attilla Danko.