Hackbart Road Hill
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Hackbart Road Hill clear sky chart from 2005-11-06 to 2025-06-10.

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	15% 12% 4 10% 6% 5% 5% 4 5% 7% 29%	120393
	Night	14% 12% 5% 10% 6% 5% 5% 4 5% 6% 29%	117798
Transparency	Day	53% 6% 12% 18% 10% 1	124012
	Night	53% 6% 11% 18% 11% 1	122340
Seeing	Day	19% 12% 29% 23% 12% 5%	15663
	Night	19% 12% 30% 27% 11% 1	24693

By Month

Percentage Cloud Cover NE (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	11% 16% 8% 18% 8% 4 5% 3 3 4 19%	3712
	11th to 20th	Day	10% 20% 10% 23% 10% 8% 5% 3 3 2 6%	4026
	21st to end	Day	16% 17% 8% 19% 7% 5% 5% 3 4 4 11%	4466
February	1st to 10th	Day	15% 19% 5% 14% 9% 7% 5% 4 3 4 15%	1800
	11th to 20th	Day	13% 14% 8% 15% 9% 6% 5% 3 5% 6% 16%	1753
	21st to end	Day	15% 16% 7% 12% 7% 5% 4 3 5% 4 20%	1605
March	1st to 10th	Day	17% 12% 5% 13% 8% 4 3 3 4 4 26%	4857
	11th to 20th	Day	11% 13% 6% 10% 5% 5% 5% 4 6% 8% 28%	4980
	21st to end	Day	17% 14% 6% 11% 5% 5% 4 3 4 5% 27%	5465
April	1st to 10th	Day	17% 16% 4 9% 5% 3 4 4 5% 7% 27%	2304
	11th to 20th	Day	18% 11% 3 7% 5% 3 4 3 5% 7% 35%	2528
	21st to end	Day	20% 11% 4 8% 4 4 3 4 4 6% 32%	2600
May	1st to 10th	Day	18% 10% 3 8% 4 5% 4 3 5% 7% 32%	5888
	11th to 20th	Day	16% 11% 3 8% 5% 4 4 4 6% 7% 32%	6040
	21st to end	Day	17% 8% 2 6% 4 4 4 3 6% 6% 38%	6949
June	1st to 10th	Day	14% 7% 2 6% 5% 6% 5% 4 6% 8% 36%	2786
	11th to 20th	Day	11% 6% 2 7% 5% 5% 6% 4 6% 9% 39%	2817
	21st to end	Day	13% 6% 3 7% 6% 4 5% 4 6% 8% 38%	2850
July	1st to 10th	Day	10% 5% 2 6% 5% 5% 6% 5% 8% 10% 37%	4760
	11th to 20th	Day	10% 6% 2 5% 5% 5% 5% 4 8% 9% 41%	4329
	21st to end	Day	9% 6% 2 6% 5% 5% 5% 5% 7% 9% 41%	4466
August	1st to 10th	Day	14% 7% 3 6% 4 5% 5% 4 7% 9% 35%	4104
	11th to 20th	Day	10% 8% 3 8% 5% 5% 6% 5% 7% 10% 33%	4044
	21st to end	Day	8% 6% 2 7% 5% 6% 6% 5% 7% 9% 39%	4445
September	1st to 10th	Day	11% 6% 3 7% 6% 4 6% 5% 6% 9% 38%	2271
	11th to 20th	Day	10% 7% 2 7% 4 4 5% 5% 6% 8% 42%	2090
	21st to end	Day	16% 8% 2 6% 5% 6% 5% 4 6% 7% 34%	2090
October	1st to 10th	Day	17% 9% 3 8% 5% 5% 5% 4 4 6% 33%	1914
	11th to 20th	Day	20% 11% 4 8% 5% 5% 4 3 5% 7% 28%	1900
	21st to end	Day	23% 13% 4 8% 5% 5% 6% 4 6% 5% 20%	2071
November	1st to 10th	Day	14% 16% 3 9% 4 4 4 3 5% 7% 30%	1737
	11th to 20th	Day	14% 16% 5% 10% 7% 5% 5% 4 6% 7% 22%	1600
	21st to end	Day	17% 19% 8% 12% 6% 4 4 4 5% 6% 16%	1600
December	1st to 10th	Day	17% 23% 9% 16% 8% 5% 4 3 4 4 9%	2600
	11th to 20th	Day	20% 20% 7% 11% 8% 4 4 3 4 3 15%	2986
	21st to end	Day	26% 21% 7% 13% 6% 4 4 2 3 3 11%	3960
January	1st to 10th	Night	13% 15% 7% 20% 8% 5% 5% 3 4 5% 16%	6229
	11th to 20th	Night	11% 15% 8% 19% 12% 8% 6% 5% 6% 4 7%	5859
	21st to end	Night	15% 15% 9% 16% 7% 6% 5% 4 5% 5% 14%	6490
February	1st to 10th	Night	15% 17% 6% 12% 9% 7% 5% 5% 4 5% 17%	2600
	11th to 20th	Night	14% 13% 5% 12% 8% 6% 6% 4 5% 7% 20%	2533
	21st to end	Night	16% 12% 4 13% 7% 6% 4 4 5% 6% 22%	2022
March	1st to 10th	Night	13% 11% 4 10% 8% 5% 5% 4 5% 6% 30%	4981
	11th to 20th	Night	9% 9% 4 10% 5% 4 5% 5% 7% 9% 33%	4979
	21st to end	Night	18% 10% 4 8% 5% 4 4 3 4 5% 34%	5467
April	1st to 10th	Night	19% 10% 3 9% 6% 4 4 4 5% 6% 30%	2095
	11th to 20th	Night	17% 10% 3 7% 5% 4 5% 3 5% 7% 35%	1837
	21st to end	Night	14% 10% 3 8% 6% 4 4 4 5% 7% 34%	1800
May	1st to 10th	Night	18% 8% 2 7% 4 4 5% 3 5% 7% 38%	4053
	11th to 20th	Night	14% 9% 4 8% 5% 5% 4 4 5% 6% 37%	3850
	21st to end	Night	18% 6% 2 4 3 3 4 3 5% 8% 44%	3926
June	1st to 10th	Night	11% 7% 2 6% 4 4 5% 4 6% 7% 44%	1598
	11th to 20th	Night	10% 5% 2 5% 4 6% 5% 4 6% 10% 42%	1358
	21st to end	Night	12% 6% 2 5% 3 5% 4 5% 6% 8% 45%	1330
July	1st to 10th	Night	5% 5% 2 5% 4 3 4 4 7% 9% 52%	2210
	11th to 20th	Night	9% 5% 2 5% 4 4 4 3 5% 8% 52%	2610
	21st to end	Night	6% 5% 2 7% 4 5% 5% 4 6% 8% 48%	3087
August	1st to 10th	Night	11% 7% 2 6% 4 4 4 3 6% 7% 45%	2825
	11th to 20th	Night	10% 8% 3 6% 4 4 5% 4 5% 9% 42%	2785
	21st to end	Night	9% 6% 2 5% 4 4 4 3 6% 7% 48%	3178
September	1st to 10th	Night	9% 6% 3 6% 5% 5% 5% 4 6% 7% 45%	1905
	11th to 20th	Night	10% 5% 2 4 3 3 3 3 5% 7% 53%	2090
	21st to end	Night	16% 8% 2 7% 4 4 5% 3 6% 7% 39%	2090
October	1st to 10th	Night	15% 8% 4 8% 5% 4 4 3 5% 6% 39%	2266
	11th to 20th	Night	18% 10% 3 7% 5% 5% 4 4 5% 7% 32%	2280
	21st to end	Night	22% 10% 3 9% 6% 5% 5% 4 6% 6% 26%	2522
November	1st to 10th	Night	14% 11% 4 8% 5% 5% 4 4 5% 7% 34%	2559
	11th to 20th	Night	16% 14% 5% 10% 6% 6% 5% 4 6% 7% 23%	2800
	21st to end	Night	18% 15% 6% 9% 6% 5% 5% 4 5% 7% 20%	2800
December	1st to 10th	Night	14% 19% 9% 16% 7% 6% 5% 4 5% 5% 11%	4580
	11th to 20th	Night	13% 22% 7% 14% 7% 5% 5% 3 4 4 16%	5208
	21st to end	Night	22% 21% 8% 12% 6% 4 4 3 4 4 12%	6996

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	68% 5% 7% 10% 9%	3713
	11th to 20th	Day	82% 7% 5% 3 2	4060
	21st to end	Day	76% 5% 8% 5% 5%	4466
February	1st to 10th	Day	71% 7% 8% 11% 3 1	1800
	11th to 20th	Day	67% 6% 9% 12% 5% 1	1762
	21st to end	Day	65% 5% 12% 12% 5% 1	1605
March	1st to 10th	Day	61% 4 13% 13% 7% 1	4860
	11th to 20th	Day	52% 5% 16% 18% 6% 2	4980
	21st to end	Day	58% 5% 10% 16% 9% 1	5465
April	1st to 10th	Day	55% 6% 11% 17% 10% 1	2304
	11th to 20th	Day	50% 5% 12% 20% 12% 1	2528
	21st to end	Day	52% 5% 11% 18% 11% 2	2600
May	1st to 10th	Day	49% 6% 12% 17% 10% 5%	5897
	11th to 20th	Day	50% 7% 11% 18% 13% 1	6044
	21st to end	Day	46% 5% 10% 19% 15% 4	6949
June	1st to 10th	Day	42% 8% 13% 21% 15% 1	2786
	11th to 20th	Day	40% 8% 12% 24% 15% 1	2817
	21st to end	Day	42% 7% 13% 24% 13%	2850
July	1st to 10th	Day	40% 5% 16% 22% 15% 2	4686
	11th to 20th	Day	37% 5% 12% 33% 12% 1	4252
	21st to end	Day	38% 6% 14% 23% 18% 1	4324
August	1st to 10th	Day	44% 6% 13% 24% 12% 1	4091
	11th to 20th	Day	45% 6% 16% 24% 9%	4083
	21st to end	Day	40% 6% 12% 31% 10% 1	4445
September	1st to 10th	Day	40% 9% 14% 24% 11% 1	2271
	11th to 20th	Day	36% 8% 14% 28% 14% 1	2090
	21st to end	Day	47% 7% 14% 23% 9% 1	2090
October	1st to 10th	Day	45% 5% 11% 21% 16% 1	3174
	11th to 20th	Day	43% 4 13% 23% 17%	3140
	21st to end	Day	55% 5% 15% 19% 6%	3397
November	1st to 10th	Day	54% 7% 13% 19% 7% 1	1737
	11th to 20th	Day	58% 8% 14% 12% 7% 1	1600
	21st to end	Day	68% 8% 12% 10% 3	1600
December	1st to 10th	Day	79% 5% 7% 7% 2	2600
	11th to 20th	Day	74% 6% 7% 9% 4	2986
	21st to end	Day	79% 5% 5% 6% 5%	3960
January	1st to 10th	Night	68% 6% 7% 14% 5%	6229
	11th to 20th	Night	75% 9% 6% 7% 3	5900
	21st to end	Night	70% 5% 9% 9% 6%	6490
February	1st to 10th	Night	67% 7% 10% 13% 3	2600
	11th to 20th	Night	61% 7% 11% 14% 6%	2535
	21st to end	Night	60% 6% 13% 14% 8%	2022
March	1st to 10th	Night	54% 5% 13% 16% 10% 1	4991
	11th to 20th	Night	44% 6% 18% 20% 10% 1	4980
	21st to end	Night	51% 5% 9% 18% 15% 2	5467
April	1st to 10th	Night	54% 5% 10% 17% 13% 1	2095
	11th to 20th	Night	47% 7% 9% 20% 15% 2	1837
	21st to end	Night	49% 5% 10% 18% 15% 3	1800
May	1st to 10th	Night	47% 5% 12% 15% 13% 8%	4060
	11th to 20th	Night	45% 8% 13% 19% 12% 3	3851
	21st to end	Night	38% 5% 13% 24% 17% 2	3927
June	1st to 10th	Night	38% 6% 11% 26% 16% 2	1598
	11th to 20th	Night	36% 7% 13% 25% 17% 2	1358
	21st to end	Night	36% 7% 14% 24% 17% 1	1330
July	1st to 10th	Night	29% 5% 15% 25% 20% 6%	2175
	11th to 20th	Night	31% 5% 12% 32% 19% 1	2564
	21st to end	Night	33% 7% 13% 27% 17% 2	2988
August	1st to 10th	Night	38% 5% 13% 26% 16% 2	2814
	11th to 20th	Night	39% 6% 16% 27% 12% 1	2812
	21st to end	Night	35% 5% 11% 33% 15% 1	3178
September	1st to 10th	Night	36% 8% 12% 27% 15% 2	1905
	11th to 20th	Night	31% 6% 13% 30% 20% 1	2090
	21st to end	Night	43% 7% 13% 25% 12%	2090
October	1st to 10th	Night	36% 4 9% 26% 24% 1	3786
	11th to 20th	Night	45% 4 15% 21% 15%	3779
	21st to end	Night	45% 5% 15% 26% 9%	4146
November	1st to 10th	Night	49% 6% 14% 21% 10% 1	2559
	11th to 20th	Night	58% 9% 12% 14% 6% 1	2800
	21st to end	Night	61% 9% 15% 11% 4 1	2800
December	1st to 10th	Night	74% 5% 11% 8% 1	4580
	11th to 20th	Night	72% 5% 8% 10% 6%	5208
	21st to end	Night	76% 5% 8% 7% 5%	6996

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% 23% 32% 15% 7% 1	225
	11th to 20th	Day	21% 19% 43% 13% 3 1	300
	21st to end	Day	25% 18% 33% 19% 4	330
February	1st to 10th	Day	27% 20% 38% 12% 3	300
	11th to 20th	Day	26% 21% 37% 15% 1	300
	21st to end	Day	29% 26% 31% 13% 1	249
March	1st to 10th	Day	26% 15% 36% 17% 5%	462
	11th to 20th	Day	22% 15% 35% 21% 6% 1	500
	21st to end	Day	27% 15% 33% 19% 5% 1	550
April	1st to 10th	Day	23% 20% 30% 20% 7% 1	500
	11th to 20th	Day	28% 16% 28% 15% 10% 4	492
	21st to end	Day	27% 12% 33% 20% 7% 2	500
May	1st to 10th	Day	21% 13% 29% 23% 10% 4	503
	11th to 20th	Day	20% 10% 28% 22% 14% 6%	527
	21st to end	Day	17% 6% 28% 27% 15% 7%	573
June	1st to 10th	Day	14% 11% 30% 28% 13% 4	526
	11th to 20th	Day	14% 9% 30% 29% 16% 3	647
	21st to end	Day	15% 8% 30% 32% 12% 3	680
July	1st to 10th	Day	8% 7% 25% 29% 22% 9%	671
	11th to 20th	Day	15% 7% 23% 27% 20% 9%	515
	21st to end	Day	11% 3 25% 33% 19% 9%	532
August	1st to 10th	Day	12% 5% 20% 28% 23% 13%	486
	11th to 20th	Day	13% 5% 18% 28% 21% 15%	479
	21st to end	Day	14% 7% 21% 30% 18% 11%	539
September	1st to 10th	Day	12% 8% 23% 26% 19% 12%	490
	11th to 20th	Day	10% 4 19% 26% 26% 14%	490
	21st to end	Day	17% 9% 27% 24% 15% 8%	490
October	1st to 10th	Day	20% 12% 28% 21% 14% 7%	490
	11th to 20th	Day	21% 16% 32% 22% 7% 2	490
	21st to end	Day	29% 16% 29% 21% 5% 1	520
November	1st to 10th	Day	22% 23% 29% 18% 8% 1	287
	11th to 20th	Day	23% 20% 33% 19% 4 2	200
	21st to end	Day	24% 20% 38% 16% 3	200
December	1st to 10th	Day	29% 22% 32% 13% 5%	200
	11th to 20th	Day	27% 26% 29% 15% 3 1	200
	21st to end	Day	32% 18% 35% 13% 2	220
January	1st to 10th	Night	22% 19% 38% 16% 5% 1	800
	11th to 20th	Night	27% 18% 32% 20% 4	800
	21st to end	Night	20% 12% 39% 24% 5%	880
February	1st to 10th	Night	21% 17% 37% 22% 2	800
	11th to 20th	Night	22% 16% 36% 21% 5%	783
	21st to end	Night	22% 17% 37% 22% 3	660
March	1st to 10th	Night	17% 16% 38% 22% 7%	800
	11th to 20th	Night	17% 19% 36% 22% 6%	800
	21st to end	Night	22% 14% 32% 24% 8% 1	880
April	1st to 10th	Night	24% 15% 31% 26% 4	800
	11th to 20th	Night	22% 15% 31% 23% 9% 1	653
	21st to end	Night	19% 12% 29% 33% 7% 1	600
May	1st to 10th	Night	17% 6% 33% 30% 13% 1	600
	11th to 20th	Night	19% 4 28% 35% 13% 1	513
	21st to end	Night	13% 4 28% 37% 17%	433
June	1st to 10th	Night	14% 4 30% 39% 13%	400
	11th to 20th	Night	12% 5% 31% 39% 13%	380
	21st to end	Night	14% 4 28% 40% 14%	380
July	1st to 10th	Night	5% 2 20% 52% 21% 1	370
	11th to 20th	Night	9% 4 24% 39% 22% 2	455
	21st to end	Night	9% 2 21% 45% 21% 1	624
August	1st to 10th	Night	11% 2 18% 41% 26% 2	567
	11th to 20th	Night	8% 3 18% 38% 29% 4	564
	21st to end	Night	12% 4 23% 33% 26% 3	655
September	1st to 10th	Night	11% 5% 23% 35% 21% 4	760
	11th to 20th	Night	12% 4 19% 33% 26% 5%	760
	21st to end	Night	18% 8% 22% 30% 18% 5%	760
October	1st to 10th	Night	19% 8% 27% 28% 16% 2	760
	11th to 20th	Night	21% 13% 27% 28% 9% 1	760
	21st to end	Night	26% 13% 30% 26% 6%	836
November	1st to 10th	Night	21% 12% 28% 28% 9% 1	780
	11th to 20th	Night	23% 15% 34% 20% 7% 1	800
	21st to end	Night	26% 15% 33% 22% 4	800
December	1st to 10th	Night	27% 18% 33% 18% 4	800
	11th to 20th	Night	21% 21% 36% 18% 3	800
	21st to end	Night	28% 17% 34% 18% 3	880

Page generated at 2025-06-07 10:28:14. Version ac07

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