Burnt Chimney
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Burnt Chimney clear sky chart from 2005-11-06 to 2026-01-17.

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% 5% 2 6% 4 4 5% 4 6% 8% 42%	126855
	Night	14% 5% 2 5% 4 4 4 4 5% 7% 46%	124820
Transparency	Day	38% 7% 12% 22% 17% 4	130461
	Night	37% 6% 11% 23% 19% 5%	129283
Seeing	Day	18% 11% 23% 25% 17% 7%	16719
	Night	16% 9% 26% 30% 17% 2	27056

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	13% 6% 2 5% 3 4 3 3 4 6% 50%	4146
	11th to 20th	Day	12% 6% 2 4 4 4 3 3 4 5% 53%	4114
	21st to end	Day	15% 7% 2 6% 5% 4 4 2 4 4 47%	4466
February	1st to 10th	Day	12% 7% 2 7% 5% 5% 5% 4 6% 7% 40%	1800
	11th to 20th	Day	19% 5% 2 5% 4 5% 4 3 5% 7% 41%	1783
	21st to end	Day	18% 8% 2 6% 4 4 4 3 5% 6% 41%	1744
March	1st to 10th	Day	18% 7% 2 6% 4 4 5% 3 6% 7% 38%	4935
	11th to 20th	Day	12% 4 1 4 3 3 3 3 5% 7% 53%	4980
	21st to end	Day	15% 6% 2 6% 4 4 5% 4 5% 6% 42%	5465
April	1st to 10th	Day	11% 6% 2 4 4 3 4 4 6% 7% 49%	2284
	11th to 20th	Day	13% 6% 2 5% 4 3 4 4 5% 8% 47%	2374
	21st to end	Day	16% 6% 2 5% 5% 4 4 3 5% 6% 43%	2510
May	1st to 10th	Day	12% 5% 2 7% 5% 6% 6% 6% 8% 10% 33%	5862
	11th to 20th	Day	21% 8% 3 7% 5% 5% 5% 4 6% 7% 30%	5861
	21st to end	Day	14% 5% 2 6% 5% 4 5% 4 6% 9% 41%	6433
June	1st to 10th	Day	10% 4 2 5% 4 6% 5% 5% 7% 9% 43%	2600
	11th to 20th	Day	9% 5% 2 6% 4 6% 6% 5% 7% 10% 40%	2600
	21st to end	Day	8% 4 2 7% 5% 5% 6% 5% 8% 9% 41%	2600
July	1st to 10th	Day	7% 5% 2 7% 5% 5% 5% 6% 8% 12% 39%	5900
	11th to 20th	Day	7% 5% 2 7% 6% 6% 8% 7% 9% 12% 31%	5900
	21st to end	Day	10% 6% 3 7% 6% 7% 7% 6% 8% 11% 30%	6424
August	1st to 10th	Day	16% 6% 2 7% 4 5% 6% 5% 8% 11% 30%	4234
	11th to 20th	Day	8% 4 2 6% 5% 6% 6% 5% 8% 11% 39%	4174
	21st to end	Day	8% 4 2 5% 4 4 4 3 6% 10% 50%	4322
September	1st to 10th	Day	13% 5% 2 5% 4 3 4 4 5% 7% 49%	2383
	11th to 20th	Day	17% 6% 2 6% 3 4 4 4 5% 8% 42%	2200
	21st to end	Day	25% 6% 3 6% 4 3 4 3 4 6% 37%	2200
October	1st to 10th	Day	17% 5% 1 4 3 4 3 3 4 5% 52%	2002
	11th to 20th	Day	15% 4 2 3 3 3 3 3 5% 6% 54%	2000
	21st to end	Day	13% 5% 2 5% 3 3 3 2 4 5% 54%	2200
November	1st to 10th	Day	12% 4 2 4 3 3 3 3 4 6% 56%	2057
	11th to 20th	Day	14% 4 2 4 4 3 3 3 4 7% 51%	1958
	21st to end	Day	13% 4 1 5% 3 3 5% 3 5% 7% 50%	1807
December	1st to 10th	Day	10% 6% 2 6% 4 4 4 3 6% 6% 49%	2680
	11th to 20th	Day	18% 5% 2 4 3 3 3 3 5% 7% 46%	3292
	21st to end	Day	21% 6% 2 5% 3 4 4 4 6% 7% 37%	4565
January	1st to 10th	Night	12% 5% 2 5% 3 3 3 3 4 5% 56%	6019
	11th to 20th	Night	13% 6% 2 5% 3 3 3 2 3 5% 56%	5979
	21st to end	Night	18% 6% 2 4 2 3 3 3 4 5% 51%	6490
February	1st to 10th	Night	15% 7% 2 5% 3 3 4 4 5% 6% 45%	2600
	11th to 20th	Night	20% 6% 2 6% 3 3 4 3 4 6% 42%	2498
	21st to end	Night	13% 6% 3 6% 4 4 5% 4 5% 7% 43%	1885
March	1st to 10th	Night	18% 6% 2 5% 4 3 4 3 5% 5% 44%	4918
	11th to 20th	Night	10% 4 1 4 3 3 4 4 5% 8% 56%	4980
	21st to end	Night	14% 6% 2 6% 4 4 5% 4 5% 6% 45%	5467
April	1st to 10th	Night	15% 7% 2 5% 4 3 4 3 5% 7% 45%	2115
	11th to 20th	Night	14% 4 1 6% 4 2 4 3 5% 7% 50%	1975
	21st to end	Night	15% 4 2 4 4 4 4 3 5% 8% 47%	1907
May	1st to 10th	Night	15% 6% 3 6% 4 4 5% 3 6% 9% 39%	4033
	11th to 20th	Night	21% 8% 3 7% 5% 4 4 3 5% 6% 34%	4032
	21st to end	Night	16% 5% 2 6% 4 4 4 4 6% 10% 41%	4421
June	1st to 10th	Night	10% 3 1 4 4 5% 6% 5% 7% 12% 42%	1800
	11th to 20th	Night	10% 5% 2 5% 4 3 4 4 7% 11% 45%	1800
	21st to end	Night	8% 3 1 5% 5% 4 4 5% 8% 12% 46%	1800
July	1st to 10th	Night	9% 6% 3 6% 5% 6% 5% 5% 7% 10% 39%	4058
	11th to 20th	Night	9% 6% 3 7% 6% 6% 6% 5% 8% 12% 32%	4057
	21st to end	Night	9% 7% 3 8% 6% 6% 6% 5% 7% 10% 33%	4427
August	1st to 10th	Night	18% 6% 2 6% 5% 5% 5% 5% 7% 11% 32%	2915
	11th to 20th	Night	8% 4 2 5% 4 5% 5% 6% 8% 11% 43%	2875
	21st to end	Night	8% 4 2 5% 4 4 4 4 6% 8% 51%	3543
September	1st to 10th	Night	11% 6% 3 6% 3 3 4 4 6% 7% 48%	2013
	11th to 20th	Night	17% 5% 2 6% 5% 4 4 3 5% 7% 43%	2200
	21st to end	Night	25% 6% 3 6% 4 4 3 3 4 5% 37%	2200
October	1st to 10th	Night	18% 5% 1 5% 3 3 4 3 4 6% 49%	2397
	11th to 20th	Night	15% 5% 2 4 3 3 4 3 4 5% 52%	2400
	21st to end	Night	15% 3 1 4 3 3 3 2 4 5% 56%	2640
November	1st to 10th	Night	14% 5% 2 5% 3 2 3 3 4 5% 53%	2461
	11th to 20th	Night	13% 4 1 4 4 3 3 3 4 5% 54%	2659
	21st to end	Night	13% 4 2 5% 4 3 4 4 5% 6% 50%	2804
December	1st to 10th	Night	10% 5% 2 4 4 3 3 3 5% 6% 54%	4720
	11th to 20th	Night	19% 6% 3 6% 5% 4 4 3 4 5% 41%	5099
	21st to end	Night	18% 5% 2 5% 4 4 4 4 5% 7% 43%	6633

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	35% 3 8% 22% 28% 6%	4147
	11th to 20th	Day	33% 4 6% 19% 29% 9%	4114
	21st to end	Day	41% 3 7% 24% 21% 4	4466
February	1st to 10th	Day	41% 6% 11% 22% 17% 3	1800
	11th to 20th	Day	42% 5% 8% 23% 17% 5%	1792
	21st to end	Day	44% 5% 12% 16% 18% 6%	1744
March	1st to 10th	Day	43% 5% 8% 20% 15% 10%	4935
	11th to 20th	Day	30% 5% 8% 23% 24% 11%	4980
	21st to end	Day	42% 6% 8% 21% 17% 5%	5465
April	1st to 10th	Day	34% 6% 12% 23% 19% 7%	2284
	11th to 20th	Day	36% 5% 12% 23% 18% 6%	2374
	21st to end	Day	42% 6% 12% 23% 14% 4	2510
May	1st to 10th	Day	43% 9% 15% 20% 11% 2	5897
	11th to 20th	Day	52% 7% 10% 20% 10% 1	5865
	21st to end	Day	37% 8% 15% 20% 16% 4	6447
June	1st to 10th	Day	35% 9% 16% 25% 14% 1	2600
	11th to 20th	Day	36% 11% 16% 20% 16% 2	2600
	21st to end	Day	35% 10% 16% 22% 15% 2	2600
July	1st to 10th	Day	36% 12% 19% 18% 11% 3	5835
	11th to 20th	Day	40% 13% 22% 19% 6%	5831
	21st to end	Day	44% 11% 15% 20% 10%	6240
August	1st to 10th	Day	45% 9% 18% 22% 5% 1	4221
	11th to 20th	Day	35% 10% 17% 27% 10% 1	4213
	21st to end	Day	30% 7% 18% 29% 15% 1	4322
September	1st to 10th	Day	34% 8% 13% 21% 20% 4	2383
	11th to 20th	Day	40% 6% 10% 24% 19% 2	2200
	21st to end	Day	49% 6% 10% 17% 17% 2	2200
October	1st to 10th	Day	32% 4 8% 20% 29% 8%	3262
	11th to 20th	Day	24% 3 7% 24% 28% 14%	3240
	21st to end	Day	25% 3 11% 26% 24% 12%	3538
November	1st to 10th	Day	30% 4 10% 23% 26% 6%	2057
	11th to 20th	Day	34% 4 8% 24% 23% 7%	1958
	21st to end	Day	33% 5% 10% 24% 25% 3	1807
December	1st to 10th	Day	35% 5% 9% 22% 23% 6%	2680
	11th to 20th	Day	39% 4 11% 20% 21% 5%	3289
	21st to end	Day	45% 6% 11% 23% 14% 1	4565
January	1st to 10th	Night	31% 3 7% 22% 28% 9%	6019
	11th to 20th	Night	32% 4 6% 19% 31% 8%	5979
	21st to end	Night	37% 3 6% 29% 19% 6%	6490
February	1st to 10th	Night	39% 5% 11% 24% 19% 2	2600
	11th to 20th	Night	44% 4 9% 20% 18% 6%	2500
	21st to end	Night	40% 6% 9% 23% 16% 6%	1885
March	1st to 10th	Night	41% 5% 7% 21% 18% 8%	4918
	11th to 20th	Night	27% 5% 8% 21% 27% 12%	4980
	21st to end	Night	39% 5% 9% 23% 20% 5%	5467
April	1st to 10th	Night	39% 5% 11% 20% 20% 5%	2115
	11th to 20th	Night	34% 5% 11% 23% 21% 6%	1975
	21st to end	Night	35% 6% 12% 25% 18% 3	1907
May	1st to 10th	Night	42% 9% 17% 20% 12% 2	4060
	11th to 20th	Night	51% 6% 11% 20% 12% 1	4033
	21st to end	Night	37% 8% 16% 26% 11% 3	4429
June	1st to 10th	Night	33% 10% 17% 24% 15% 1	1800
	11th to 20th	Night	32% 10% 18% 22% 16% 2	1800
	21st to end	Night	30% 11% 17% 23% 17% 4	1800
July	1st to 10th	Night	39% 12% 16% 19% 11% 2	4015
	11th to 20th	Night	44% 12% 20% 18% 5% 1	4006
	21st to end	Night	44% 11% 15% 21% 10%	4297
August	1st to 10th	Night	46% 8% 18% 21% 7% 1	2904
	11th to 20th	Night	33% 9% 18% 28% 11% 1	2902
	21st to end	Night	31% 7% 13% 36% 11% 2	3543
September	1st to 10th	Night	36% 8% 12% 21% 17% 6%	2013
	11th to 20th	Night	41% 6% 10% 21% 20% 2	2200
	21st to end	Night	51% 5% 9% 18% 15% 3	2200
October	1st to 10th	Night	37% 4 8% 18% 26% 7%	3917
	11th to 20th	Night	25% 3 7% 22% 30% 12%	3899
	21st to end	Night	23% 3 7% 28% 27% 12%	4252
November	1st to 10th	Night	34% 4 9% 21% 25% 6%	2461
	11th to 20th	Night	32% 4 8% 22% 25% 8%	2659
	21st to end	Night	34% 5% 9% 25% 23% 6%	2804
December	1st to 10th	Night	31% 4 8% 28% 25% 3	4720
	11th to 20th	Night	46% 4 9% 19% 14% 7%	5101
	21st to end	Night	40% 5% 13% 24% 17% 2	6633

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	25% 25% 30% 15% 4 1	330
	11th to 20th	Day	27% 22% 33% 16% 1	318
	21st to end	Day	23% 25% 35% 14% 3	330
February	1st to 10th	Day	19% 21% 36% 17% 6%	300
	11th to 20th	Day	36% 23% 33% 5% 2 1	300
	21st to end	Day	25% 21% 31% 20% 3	343
March	1st to 10th	Day	22% 17% 30% 23% 7%	500
	11th to 20th	Day	22% 20% 29% 20% 7% 1	500
	21st to end	Day	24% 16% 32% 23% 5%	550
April	1st to 10th	Day	20% 21% 28% 23% 8% 1	500
	11th to 20th	Day	17% 15% 29% 23% 12% 4	492
	21st to end	Day	19% 12% 32% 23% 12% 2	500
May	1st to 10th	Day	17% 15% 31% 23% 10% 4	503
	11th to 20th	Day	20% 7% 24% 27% 14% 7%	527
	21st to end	Day	19% 5% 19% 27% 22% 9%	573
June	1st to 10th	Day	9% 5% 24% 35% 17% 9%	530
	11th to 20th	Day	9% 6% 15% 30% 26% 12%	530
	21st to end	Day	9% 3 19% 28% 30% 10%	530
July	1st to 10th	Day	10% 3 13% 26% 30% 18%	525
	11th to 20th	Day	7% 2 10% 27% 37% 17%	524
	21st to end	Day	11% 2 11% 30% 28% 18%	576
August	1st to 10th	Day	16% 4 16% 23% 29% 12%	526
	11th to 20th	Day	12% 2 11% 28% 28% 19%	519
	21st to end	Day	9% 3 10% 27% 30% 20%	583
September	1st to 10th	Day	15% 2 12% 25% 28% 18%	530
	11th to 20th	Day	19% 4 11% 24% 28% 16%	530
	21st to end	Day	28% 6% 17% 26% 18% 4	530
October	1st to 10th	Day	20% 4 16% 30% 21% 8%	530
	11th to 20th	Day	15% 11% 23% 25% 23% 4	530
	21st to end	Day	17% 11% 25% 27% 16% 4	583
November	1st to 10th	Day	16% 10% 25% 31% 16% 2	535
	11th to 20th	Day	18% 18% 28% 25% 10% 2	398
	21st to end	Day	18% 20% 26% 26% 9% 1	286
December	1st to 10th	Day	25% 19% 31% 21% 5%	220
	11th to 20th	Day	24% 15% 31% 23% 7% 1	275
	21st to end	Day	25% 16% 31% 19% 7% 1	363
January	1st to 10th	Night	20% 18% 35% 24% 4	840
	11th to 20th	Night	18% 16% 37% 28% 2	825
	21st to end	Night	19% 12% 41% 25% 2	880
February	1st to 10th	Night	18% 14% 38% 28% 2	800
	11th to 20th	Night	25% 16% 40% 19% 1	783
	21st to end	Night	19% 14% 41% 23% 3	660
March	1st to 10th	Night	16% 15% 37% 28% 4	800
	11th to 20th	Night	19% 14% 35% 24% 8% 1	800
	21st to end	Night	18% 11% 36% 30% 5%	880
April	1st to 10th	Night	19% 18% 30% 27% 6%	800
	11th to 20th	Night	15% 11% 35% 27% 12%	791
	21st to end	Night	16% 7% 31% 35% 11%	707
May	1st to 10th	Night	15% 8% 31% 31% 15%	600
	11th to 20th	Night	20% 5% 23% 32% 18% 2	591
	21st to end	Night	15% 3 15% 31% 32% 4	650
June	1st to 10th	Night	10% 2 15% 40% 31% 2	600
	11th to 20th	Night	11% 2 13% 33% 37% 5%	600
	21st to end	Night	8% 3 12% 40% 33% 5%	600
July	1st to 10th	Night	10% 2 9% 32% 40% 7%	585
	11th to 20th	Night	7% 1 8% 33% 45% 6%	582
	21st to end	Night	7% 3 9% 39% 37% 5%	657
August	1st to 10th	Night	16% 2 8% 33% 37% 5%	597
	11th to 20th	Night	11% 2 8% 37% 37% 5%	594
	21st to end	Night	11% 2 10% 33% 38% 8%	850
September	1st to 10th	Night	13% 2 10% 31% 37% 7%	800
	11th to 20th	Night	18% 2 11% 31% 33% 5%	800
	21st to end	Night	27% 5% 16% 28% 23% 2	800
October	1st to 10th	Night	19% 5% 17% 28% 27% 5%	800
	11th to 20th	Night	17% 7% 24% 33% 17% 2	800
	21st to end	Night	16% 9% 24% 36% 13% 1	880
November	1st to 10th	Night	16% 8% 27% 34% 13% 2	820
	11th to 20th	Night	15% 11% 31% 31% 10% 1	840
	21st to end	Night	16% 13% 30% 31% 10% 1	840
December	1st to 10th	Night	21% 11% 35% 28% 5%	840
	11th to 20th	Night	18% 10% 39% 28% 5%	840
	21st to end	Night	21% 12% 32% 30% 4	924

Page generated at 2026-01-14 01:14:27. Version ac07

Copyright © 2026 Attilla Danko.