Taylor Dark Sky Site
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Taylor Dark Sky Site clear sky chart from 2005-11-06 to 2026-06-16.

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% 5% 4 5% 4 6% 8% 38%	137318
	Night	14% 8% 3 7% 4 4 4 3 5% 7% 40%	134943
Transparency	Day	42% 7% 12% 23% 15% 2	140890
	Night	42% 6% 11% 23% 16% 2	139435
Seeing	Day	15% 10% 26% 25% 18% 7%	17761
	Night	17% 9% 28% 31% 14% 2	27605

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	12% 10% 6% 11% 5% 5% 5% 3 5% 6% 31%	4691
	11th to 20th	Day	10% 9% 4 13% 7% 7% 5% 4 5% 6% 29%	4710
	21st to end	Day	18% 14% 4 10% 7% 4 5% 3 4 4 28%	5609
February	1st to 10th	Day	16% 12% 5% 9% 4 4 4 3 5% 6% 32%	2050
	11th to 20th	Day	16% 11% 3 9% 5% 5% 4 4 4 7% 32%	2048
	21st to end	Day	15% 11% 4 8% 5% 4 5% 3 5% 5% 35%	1730
March	1st to 10th	Day	18% 12% 3 7% 4 4 3 2 3 4 40%	4580
	11th to 20th	Day	10% 10% 2 6% 4 3 4 3 5% 7% 45%	4773
	21st to end	Day	16% 9% 3 8% 5% 5% 5% 4 6% 7% 32%	6099
April	1st to 10th	Day	16% 7% 3 7% 5% 4 4 3 5% 7% 39%	2520
	11th to 20th	Day	15% 8% 3 7% 5% 4 3 4 5% 6% 40%	2494
	21st to end	Day	18% 7% 2 7% 4 5% 4 3 6% 6% 38%	2567
May	1st to 10th	Day	16% 7% 2 8% 5% 5% 5% 5% 7% 10% 30%	7616
	11th to 20th	Day	16% 7% 3 6% 4 4 4 4 5% 7% 40%	7626
	21st to end	Day	14% 7% 3 9% 6% 6% 6% 5% 7% 9% 30%	8963
June	1st to 10th	Day	11% 6% 2 5% 4 4 4 4 6% 9% 45%	2940
	11th to 20th	Day	8% 5% 2 6% 5% 5% 4 4 6% 7% 48%	2871
	21st to end	Day	8% 6% 2 6% 4 4 5% 5% 7% 9% 44%	2800
July	1st to 10th	Day	10% 5% 2 6% 4 4 5% 4 6% 11% 44%	6360
	11th to 20th	Day	8% 6% 2 8% 5% 5% 6% 5% 8% 12% 36%	6360
	21st to end	Day	9% 6% 2 7% 5% 6% 7% 6% 8% 10% 34%	6924
August	1st to 10th	Day	8% 4 2 4 4 3 4 4 6% 10% 53%	4118
	11th to 20th	Day	8% 5% 2 6% 5% 5% 5% 5% 8% 11% 42%	3849
	21st to end	Day	5% 4 2 4 4 4 4 4 7% 10% 52%	4312
September	1st to 10th	Day	11% 5% 2 6% 5% 4 4 4 6% 7% 47%	2400
	11th to 20th	Day	9% 4 2 5% 4 4 5% 4 6% 7% 51%	2250
	21st to end	Day	11% 5% 2 5% 4 4 3 3 5% 7% 52%	2200
October	1st to 10th	Day	11% 4 2 5% 3 3 4 3 4 7% 54%	2198
	11th to 20th	Day	14% 5% 2 5% 3 4 4 3 5% 6% 48%	2000
	21st to end	Day	20% 7% 3 5% 3 3 4 3 5% 5% 43%	2010
November	1st to 10th	Day	10% 6% 2 6% 4 3 3 2 5% 7% 52%	1852
	11th to 20th	Day	16% 10% 3 6% 5% 3 3 3 4 7% 42%	1890
	21st to end	Day	17% 10% 4 8% 4 4 4 3 4 4 38%	1890
December	1st to 10th	Day	11% 10% 4 7% 4 4 4 3 4 5% 45%	2860
	11th to 20th	Day	15% 11% 5% 10% 5% 5% 5% 3 4 6% 30%	3088
	21st to end	Day	29% 16% 5% 10% 5% 4 3 3 3 4 18%	4070
January	1st to 10th	Night	15% 11% 7% 10% 4 4 4 3 5% 6% 33%	8232
	11th to 20th	Night	12% 12% 4 11% 5% 6% 6% 3 4 5% 32%	8280
	21st to end	Night	18% 10% 5% 8% 5% 4 4 3 5% 6% 32%	8603
February	1st to 10th	Night	19% 9% 4 9% 5% 4 4 4 5% 6% 32%	2567
	11th to 20th	Night	17% 9% 3 8% 5% 5% 3 3 4 6% 37%	2458
	21st to end	Night	19% 8% 3 7% 4 3 4 3 4 5% 39%	2076
March	1st to 10th	Night	19% 13% 4 7% 4 3 3 3 4 5% 36%	5493
	11th to 20th	Night	13% 7% 2 5% 4 4 4 3 4 7% 48%	5435
	21st to end	Night	18% 9% 3 7% 5% 5% 4 4 5% 6% 34%	5072
April	1st to 10th	Night	13% 7% 3 7% 5% 4 4 3 5% 6% 43%	2100
	11th to 20th	Night	16% 7% 3 5% 4 4 3 3 5% 7% 44%	2075
	21st to end	Night	16% 8% 2 6% 4 4 4 4 5% 8% 37%	2053
May	1st to 10th	Night	16% 8% 3 8% 5% 4 5% 4 6% 8% 33%	5237
	11th to 20th	Night	14% 6% 3 6% 4 4 4 4 6% 9% 40%	5234
	21st to end	Night	14% 7% 3 9% 4 5% 5% 4 6% 9% 33%	5202
June	1st to 10th	Night	10% 6% 2 6% 4 4 3 4 6% 7% 48%	1680
	11th to 20th	Night	8% 5% 2 5% 3 4 6% 3 6% 7% 50%	1640
	21st to end	Night	6% 4 3 5% 4 4 5% 5% 7% 10% 48%	1600
July	1st to 10th	Night	10% 5% 2 5% 4 4 4 4 5% 9% 48%	3618
	11th to 20th	Night	6% 4 2 6% 6% 6% 5% 5% 7% 9% 45%	3617
	21st to end	Night	8% 6% 3 8% 5% 5% 5% 5% 8% 10% 38%	3947
August	1st to 10th	Night	6% 3 1 5% 3 4 4 4 5% 9% 55%	3028
	11th to 20th	Night	7% 4 2 5% 4 5% 5% 4 6% 8% 52%	3200
	21st to end	Night	4 3 1 4 3 4 4 4 6% 10% 57%	3586
September	1st to 10th	Night	11% 5% 2 5% 3 4 3 3 5% 7% 54%	2000
	11th to 20th	Night	7% 4 2 5% 4 3 4 3 6% 7% 57%	2128
	21st to end	Night	12% 5% 2 5% 3 4 4 3 5% 7% 51%	2200
October	1st to 10th	Night	8% 4 2 4 3 3 4 3 4 5% 59%	2200
	11th to 20th	Night	15% 5% 2 4 3 3 3 3 3 6% 53%	2398
	21st to end	Night	18% 8% 3 5% 4 4 3 3 5% 5% 43%	2829
November	1st to 10th	Night	10% 6% 2 6% 3 3 4 3 5% 5% 53%	2666
	11th to 20th	Night	13% 9% 2 5% 4 4 3 3 5% 6% 46%	2730
	21st to end	Night	20% 9% 3 6% 4 4 3 2 5% 5% 39%	2730
December	1st to 10th	Night	15% 9% 3 7% 4 3 3 3 4 5% 43%	4540
	11th to 20th	Night	18% 8% 4 7% 4 4 4 3 5% 6% 37%	5339
	21st to end	Night	30% 15% 4 7% 4 4 3 3 4 4 21%	7150

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	52% 5% 12% 22% 8% 1	4692
	11th to 20th	Day	53% 6% 11% 17% 11% 2	4710
	21st to end	Day	60% 5% 8% 18% 7% 3	5609
February	1st to 10th	Day	52% 5% 11% 21% 8% 2	2050
	11th to 20th	Day	51% 5% 11% 20% 11% 2	2058
	21st to end	Day	49% 6% 9% 22% 11% 3	1730
March	1st to 10th	Day	49% 4 5% 19% 18% 4	4580
	11th to 20th	Day	37% 5% 11% 31% 15% 2	4773
	21st to end	Day	47% 8% 12% 23% 8% 1	6101
April	1st to 10th	Day	43% 7% 13% 22% 14% 1	2520
	11th to 20th	Day	43% 6% 11% 24% 13% 2	2494
	21st to end	Day	45% 6% 11% 25% 11% 3	2567
May	1st to 10th	Day	45% 9% 15% 20% 11%	7651
	11th to 20th	Day	43% 7% 11% 22% 16% 1	7630
	21st to end	Day	47% 9% 12% 19% 13% 1	8977
June	1st to 10th	Day	34% 8% 14% 23% 18% 4	2940
	11th to 20th	Day	34% 7% 12% 22% 21% 4	2871
	21st to end	Day	34% 10% 15% 21% 16% 4	2800
July	1st to 10th	Day	33% 7% 11% 29% 18% 2	6291
	11th to 20th	Day	37% 10% 15% 25% 12% 1	6285
	21st to end	Day	41% 11% 16% 23% 9% 1	6728
August	1st to 10th	Day	26% 7% 14% 36% 16% 1	4103
	11th to 20th	Day	34% 8% 15% 26% 16% 1	3885
	21st to end	Day	26% 7% 16% 32% 15% 4	4311
September	1st to 10th	Day	35% 7% 11% 23% 20% 5%	2400
	11th to 20th	Day	31% 6% 12% 25% 24% 3	2250
	21st to end	Day	33% 4 11% 23% 26% 4	2200
October	1st to 10th	Day	20% 4 7% 25% 40% 4	3575
	11th to 20th	Day	26% 4 9% 24% 35% 3	3240
	21st to end	Day	36% 3 8% 24% 28% 1	3222
November	1st to 10th	Day	33% 4 10% 30% 17% 5%	1852
	11th to 20th	Day	44% 4 9% 22% 17% 5%	1890
	21st to end	Day	49% 6% 8% 21% 15% 1	1890
December	1st to 10th	Day	41% 5% 13% 27% 13%	2860
	11th to 20th	Day	55% 5% 9% 22% 7% 1	3085
	21st to end	Day	69% 6% 11% 11% 4	4070
January	1st to 10th	Night	52% 5% 12% 22% 7%	8233
	11th to 20th	Night	55% 4 8% 15% 15% 3	8280
	21st to end	Night	53% 4 10% 21% 10% 1	8603
February	1st to 10th	Night	53% 7% 12% 19% 9% 1	2567
	11th to 20th	Night	49% 4 11% 20% 14% 2	2459
	21st to end	Night	48% 5% 11% 23% 12% 2	2076
March	1st to 10th	Night	51% 5% 6% 21% 14% 3	5493
	11th to 20th	Night	36% 6% 10% 26% 21% 2	5435
	21st to end	Night	49% 6% 11% 25% 8% 1	5072
April	1st to 10th	Night	40% 6% 11% 25% 14% 3	2100
	11th to 20th	Night	39% 6% 11% 21% 20% 4	2075
	21st to end	Night	44% 7% 11% 23% 12% 3	2053
May	1st to 10th	Night	47% 9% 13% 22% 9% 1	5264
	11th to 20th	Night	40% 7% 13% 22% 18% 1	5235
	21st to end	Night	44% 9% 13% 19% 12% 2	5212
June	1st to 10th	Night	34% 5% 11% 25% 22% 4	1680
	11th to 20th	Night	30% 8% 10% 23% 23% 6%	1640
	21st to end	Night	29% 9% 14% 22% 19% 7%	1600
July	1st to 10th	Night	33% 7% 10% 24% 23% 3	3580
	11th to 20th	Night	33% 9% 14% 26% 16% 1	3572
	21st to end	Night	38% 10% 17% 23% 12% 1	3832
August	1st to 10th	Night	24% 7% 16% 37% 15% 1	3019
	11th to 20th	Night	28% 8% 13% 30% 20% 1	3230
	21st to end	Night	22% 7% 15% 30% 22% 4	3586
September	1st to 10th	Night	30% 5% 10% 27% 21% 6%	2000
	11th to 20th	Night	25% 5% 9% 27% 28% 5%	2128
	21st to end	Night	33% 5% 11% 21% 25% 6%	2200
October	1st to 10th	Night	17% 4 7% 22% 45% 5%	3590
	11th to 20th	Night	24% 3 8% 26% 36% 4	3897
	21st to end	Night	33% 4 8% 24% 25% 5%	4567
November	1st to 10th	Night	33% 5% 11% 24% 22% 5%	2666
	11th to 20th	Night	38% 4 10% 24% 21% 3	2730
	21st to end	Night	48% 4 11% 22% 15% 1	2730
December	1st to 10th	Night	44% 4 11% 25% 15%	4540
	11th to 20th	Night	47% 6% 13% 22% 12%	5341
	21st to end	Night	67% 5% 10% 13% 5% 1	7150

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	22% 17% 33% 21% 7% 1	330
	11th to 20th	Day	25% 19% 35% 19% 2	330
	21st to end	Day	21% 18% 39% 17% 4	363
February	1st to 10th	Day	23% 16% 39% 17% 5%	330
	11th to 20th	Day	23% 23% 33% 16% 3 2	330
	21st to end	Day	25% 16% 36% 19% 4	273
March	1st to 10th	Day	22% 20% 36% 19% 2	330
	11th to 20th	Day	25% 19% 38% 14% 5%	366
	21st to end	Day	26% 16% 36% 18% 5% 1	594
April	1st to 10th	Day	19% 15% 34% 24% 6% 1	540
	11th to 20th	Day	18% 17% 29% 21% 13% 2	532
	21st to end	Day	19% 13% 34% 23% 9% 2	540
May	1st to 10th	Day	19% 13% 30% 24% 11% 2	543
	11th to 20th	Day	19% 9% 26% 26% 14% 7%	567
	21st to end	Day	10% 7% 29% 28% 17% 9%	812
June	1st to 10th	Day	12% 6% 22% 29% 23% 7%	780
	11th to 20th	Day	10% 5% 23% 33% 23% 7%	756
	21st to end	Day	8% 5% 27% 28% 23% 9%	730
July	1st to 10th	Day	9% 3 13% 26% 28% 20%	721
	11th to 20th	Day	7% 3 14% 35% 26% 14%	718
	21st to end	Day	9% 3 13% 31% 32% 11%	794
August	1st to 10th	Day	10% 4 11% 27% 34% 15%	556
	11th to 20th	Day	10% 3 14% 28% 30% 14%	519
	21st to end	Day	5% 1 13% 25% 39% 17%	583
September	1st to 10th	Day	10% 3 15% 26% 33% 13%	530
	11th to 20th	Day	8% 1 11% 29% 33% 18%	530
	21st to end	Day	15% 4 22% 23% 23% 13%	530
October	1st to 10th	Day	9% 3 23% 31% 26% 8%	528
	11th to 20th	Day	12% 12% 34% 24% 14% 4	330
	21st to end	Day	25% 17% 31% 22% 5% 1	363
November	1st to 10th	Day	13% 12% 34% 24% 13% 4	330
	11th to 20th	Day	17% 20% 31% 21% 9% 2	330
	21st to end	Day	22% 15% 29% 25% 8%	330
December	1st to 10th	Day	12% 20% 41% 19% 5% 3	330
	11th to 20th	Day	22% 14% 38% 19% 7%	330
	21st to end	Day	29% 16% 33% 16% 5% 1	363
January	1st to 10th	Night	19% 14% 37% 26% 4	1050
	11th to 20th	Night	24% 14% 38% 21% 4	1050
	21st to end	Night	20% 14% 39% 25% 3	1155
February	1st to 10th	Night	23% 11% 39% 25% 2	887
	11th to 20th	Night	22% 15% 35% 26% 2	823
	21st to end	Night	23% 13% 40% 23% 1	692
March	1st to 10th	Night	23% 14% 34% 25% 4	840
	11th to 20th	Night	21% 12% 37% 24% 5%	830
	21st to end	Night	23% 10% 32% 29% 5%	693
April	1st to 10th	Night	16% 13% 33% 32% 6%	630
	11th to 20th	Night	19% 11% 29% 30% 11%	623
	21st to end	Night	20% 8% 33% 31% 7% 1	630
May	1st to 10th	Night	16% 7% 34% 33% 9% 1	630
	11th to 20th	Night	15% 6% 26% 36% 16% 2	621
	21st to end	Night	12% 4 20% 38% 25% 2	683
June	1st to 10th	Night	11% 5% 21% 41% 21% 1	630
	11th to 20th	Night	9% 4 18% 45% 24% 1	615
	21st to end	Night	7% 2 22% 40% 29% 1	600
July	1st to 10th	Night	9% 3 12% 33% 36% 8%	585
	11th to 20th	Night	5% 3 13% 38% 35% 4	582
	21st to end	Night	7% 2 12% 41% 34% 4	657
August	1st to 10th	Night	8% 2 9% 42% 35% 5%	597
	11th to 20th	Night	6% 1 10% 42% 37% 4	594
	21st to end	Night	6% 2 10% 35% 42% 6%	660
September	1st to 10th	Night	12% 3 12% 35% 34% 5%	600
	11th to 20th	Night	7% 2 13% 36% 37% 4	728
	21st to end	Night	14% 4 20% 30% 28% 4	800
October	1st to 10th	Night	9% 5% 21% 38% 23% 4	800
	11th to 20th	Night	17% 9% 28% 30% 15% 1	800
	21st to end	Night	22% 10% 33% 27% 7%	880
November	1st to 10th	Night	13% 8% 35% 31% 11% 1	820
	11th to 20th	Night	16% 12% 33% 30% 9%	840
	21st to end	Night	24% 12% 30% 27% 7%	840
December	1st to 10th	Night	21% 10% 38% 25% 5%	935
	11th to 20th	Night	23% 9% 34% 27% 6% 1	1050
	21st to end	Night	32% 12% 32% 21% 4	1155

Page generated at 2026-06-13 01:31:43. Version ac07

Copyright © 2026 Attilla Danko.