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 2026-10-14.

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% 11% 4 10% 6% 5% 5% 4 5% 7% 30%	150639
	Night	13% 11% 5% 10% 6% 5% 5% 4 5% 6% 30%	141093
Transparency	Day	52% 5% 11% 20% 11% 1	154218
	Night	53% 5% 11% 18% 11% 1	145603
Seeing	Day	20% 12% 29% 23% 11% 5%	17505
	Night	19% 12% 30% 27% 11% 1	26341

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	14% 16% 9% 18% 9% 4 5% 3 3 3 16%	4818
	11th to 20th	Day	9% 21% 11% 23% 10% 9% 4 2 2 2 5%	5246
	21st to end	Day	13% 15% 7% 19% 10% 9% 6% 4 4 4 9%	5780
February	1st to 10th	Day	14% 19% 5% 14% 9% 7% 5% 4 3 3 16%	1890
	11th to 20th	Day	13% 13% 8% 15% 9% 6% 6% 3 5% 6% 16%	1843
	21st to end	Day	15% 16% 7% 12% 7% 5% 4 3 5% 5% 20%	1683
March	1st to 10th	Day	17% 12% 5% 13% 8% 4 3 3 4 4 26%	4965
	11th to 20th	Day	11% 13% 6% 10% 5% 5% 5% 4 6% 8% 28%	5090
	21st to end	Day	17% 14% 6% 11% 5% 5% 4 3 4 5% 27%	5586
April	1st to 10th	Day	16% 16% 4 9% 5% 3 4 4 5% 7% 27%	2419
	11th to 20th	Day	18% 11% 3 7% 5% 3 4 3 4 6% 34%	2656
	21st to end	Day	19% 11% 3 8% 4 4 3 3 5% 6% 32%	2730
May	1st to 10th	Day	16% 9% 3 8% 5% 5% 5% 4 5% 8% 33%	7642
	11th to 20th	Day	15% 11% 3 8% 5% 4 4 4 6% 8% 33%	7861
	21st to end	Day	17% 7% 2 6% 4 4 4 3 5% 6% 42%	9060
June	1st to 10th	Day	13% 7% 2 6% 5% 5% 5% 5% 6% 8% 37%	2940
	11th to 20th	Day	11% 6% 2 8% 6% 4 6% 4 6% 9% 38%	3113
	21st to end	Day	13% 6% 3 7% 6% 4 5% 4 6% 8% 39%	3150
July	1st to 10th	Day	10% 7% 3 7% 5% 5% 5% 4 7% 10% 38%	8879
	11th to 20th	Day	7% 5% 2 6% 4 5% 5% 4 7% 10% 45%	8085
	21st to end	Day	8% 5% 2 6% 5% 5% 5% 4 7% 9% 44%	8340
August	1st to 10th	Day	16% 8% 3 6% 4 5% 5% 4 6% 7% 37%	6014
	11th to 20th	Day	9% 7% 3 7% 5% 5% 6% 5% 7% 10% 36%	5951
	21st to end	Day	10% 7% 3 8% 5% 5% 6% 5% 7% 9% 35%	6462
September	1st to 10th	Day	11% 6% 3 6% 6% 4 6% 5% 6% 10% 38%	2510
	11th to 20th	Day	10% 6% 2 7% 3 5% 5% 5% 6% 8% 43%	2310
	21st to end	Day	15% 8% 2 7% 5% 5% 4 4 6% 7% 35%	2310
October	1st to 10th	Day	16% 9% 3 8% 5% 4 5% 4 4 6% 36%	2116
	11th to 20th	Day	20% 11% 4 8% 5% 5% 4 3 5% 7% 28%	2030
	21st to end	Day	23% 13% 4 8% 5% 5% 6% 4 6% 5% 21%	2180
November	1st to 10th	Day	14% 16% 4 9% 4 4 4 3 4 7% 30%	1826
	11th to 20th	Day	14% 17% 4 10% 7% 5% 5% 4 6% 7% 22%	1680
	21st to end	Day	16% 19% 8% 12% 7% 4 4 4 5% 6% 15%	1680
December	1st to 10th	Day	17% 23% 9% 16% 7% 5% 4 3 4 4 9%	2680
	11th to 20th	Day	20% 20% 7% 12% 8% 4 5% 3 4 3 14%	3066
	21st to end	Day	26% 21% 7% 14% 6% 4 4 2 3 3 10%	4048
January	1st to 10th	Night	13% 14% 7% 21% 8% 6% 5% 3 4 5% 13%	8072
	11th to 20th	Night	9% 18% 9% 20% 13% 8% 5% 4 5% 4 6%	7639
	21st to end	Night	12% 13% 8% 15% 9% 8% 6% 4 5% 5% 13%	8401
February	1st to 10th	Night	14% 16% 5% 12% 9% 7% 5% 5% 4 5% 18%	2730
	11th to 20th	Night	13% 13% 5% 13% 8% 6% 6% 4 5% 7% 21%	2663
	21st to end	Night	15% 13% 4 13% 7% 6% 4 4 5% 6% 22%	2120
March	1st to 10th	Night	13% 11% 4 10% 8% 5% 5% 3 5% 6% 30%	5093
	11th to 20th	Night	9% 9% 4 10% 5% 4 5% 5% 7% 9% 33%	5089
	21st to end	Night	18% 10% 4 9% 5% 4 4 3 4 5% 34%	5588
April	1st to 10th	Night	19% 10% 4 9% 6% 4 5% 4 5% 6% 30%	2200
	11th to 20th	Night	16% 10% 3 7% 5% 4 5% 3 5% 7% 35%	1930
	21st to end	Night	14% 10% 3 8% 6% 4 4 4 5% 7% 34%	1890
May	1st to 10th	Night	17% 8% 3 7% 4 4 5% 3 5% 7% 38%	5257
	11th to 20th	Night	14% 10% 3 7% 5% 5% 4 3 5% 6% 37%	4996
	21st to end	Night	18% 6% 2 4 3 3 3 2 5% 7% 46%	5114
June	1st to 10th	Night	11% 7% 2 6% 4 4 5% 4 5% 7% 45%	1680
	11th to 20th	Night	10% 6% 2 6% 5% 6% 4 4 6% 10% 41%	1500
	21st to end	Night	11% 6% 2 5% 4 5% 4 4 5% 8% 46%	1470
July	1st to 10th	Night	7% 5% 2 6% 4 4 4 4 7% 9% 48%	4110
	11th to 20th	Night	8% 6% 2 6% 4 4 4 4 5% 9% 49%	4858
	21st to end	Night	8% 6% 2 7% 4 4 4 3 5% 7% 50%	5737
August	1st to 10th	Night	13% 8% 3 7% 4 4 4 3 6% 6% 42%	4135
	11th to 20th	Night	9% 8% 3 7% 5% 4 5% 4 5% 9% 44%	4095
	21st to end	Night	12% 7% 3 6% 4 5% 5% 4 6% 7% 42%	4616
September	1st to 10th	Night	9% 6% 3 6% 5% 5% 5% 4 6% 8% 44%	2106
	11th to 20th	Night	9% 5% 2 4 4 3 4 4 5% 7% 54%	2310
	21st to end	Night	15% 7% 2 7% 4 4 4 3 6% 7% 40%	2310
October	1st to 10th	Night	14% 7% 3 8% 4 4 4 3 5% 6% 41%	2504
	11th to 20th	Night	19% 10% 3 7% 5% 5% 4 4 5% 7% 32%	2437
	21st to end	Night	21% 10% 3 9% 6% 5% 5% 4 6% 6% 27%	2655
November	1st to 10th	Night	14% 11% 4 8% 5% 5% 4 4 5% 6% 34%	2690
	11th to 20th	Night	15% 14% 5% 10% 6% 6% 5% 4 6% 7% 23%	2940
	21st to end	Night	18% 16% 6% 9% 6% 5% 4 4 5% 7% 19%	2940
December	1st to 10th	Night	13% 19% 9% 15% 7% 6% 5% 4 5% 5% 11%	4720
	11th to 20th	Night	12% 22% 7% 14% 7% 5% 5% 3 4 4 17%	5348
	21st to end	Night	22% 21% 8% 13% 6% 4 4 3 4 4 12%	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	72% 5% 7% 9% 7%	4819
	11th to 20th	Day	85% 5% 4 3 3	5280
	21st to end	Day	77% 4 8% 5% 5%	5780
February	1st to 10th	Day	71% 6% 7% 11% 4 1	1890
	11th to 20th	Day	67% 6% 8% 13% 5% 1	1852
	21st to end	Day	65% 5% 12% 12% 6% 1	1683
March	1st to 10th	Day	61% 4 13% 13% 7% 1	4968
	11th to 20th	Day	53% 5% 15% 18% 6% 2	5090
	21st to end	Day	59% 5% 10% 16% 9% 1	5586
April	1st to 10th	Day	56% 6% 11% 17% 11%	2419
	11th to 20th	Day	51% 5% 12% 21% 11% 1	2656
	21st to end	Day	52% 5% 11% 19% 10% 2	2730
May	1st to 10th	Day	48% 5% 12% 20% 11% 4	7651
	11th to 20th	Day	48% 6% 11% 20% 14% 1	7865
	21st to end	Day	43% 4 8% 25% 17% 3	9061
June	1st to 10th	Day	42% 7% 12% 21% 16% 1	2940
	11th to 20th	Day	41% 7% 12% 24% 15% 1	3113
	21st to end	Day	42% 6% 14% 25% 13%	3150
July	1st to 10th	Day	41% 3 14% 25% 15% 1	8806
	11th to 20th	Day	33% 3 12% 35% 15% 1	8008
	21st to end	Day	36% 4 14% 27% 19% 1	8156
August	1st to 10th	Day	46% 4 13% 19% 15% 3	6001
	11th to 20th	Day	42% 5% 17% 29% 7%	5990
	21st to end	Day	44% 4 14% 30% 8%	6462
September	1st to 10th	Day	40% 8% 14% 25% 11% 1	2510
	11th to 20th	Day	36% 7% 14% 28% 14% 1	2310
	21st to end	Day	47% 6% 13% 23% 10% 1	2310
October	1st to 10th	Day	44% 4 11% 23% 16% 1	3376
	11th to 20th	Day	44% 4 13% 23% 17%	3270
	21st to end	Day	55% 4 14% 19% 7%	3506
November	1st to 10th	Day	54% 6% 13% 19% 7% 1	1826
	11th to 20th	Day	58% 8% 13% 13% 8% 1	1680
	21st to end	Day	68% 7% 11% 10% 3	1680
December	1st to 10th	Day	79% 5% 7% 7% 2	2680
	11th to 20th	Day	74% 6% 7% 9% 5%	3066
	21st to end	Day	79% 5% 5% 6% 5%	4048
January	1st to 10th	Night	72% 5% 7% 12% 4	8072
	11th to 20th	Night	78% 7% 5% 6% 3	7680
	21st to end	Night	71% 5% 8% 9% 7%	8401
February	1st to 10th	Night	66% 7% 10% 13% 4 1	2730
	11th to 20th	Night	60% 7% 11% 14% 6%	2665
	21st to end	Night	60% 6% 12% 14% 7%	2120
March	1st to 10th	Night	54% 5% 13% 16% 10% 1	5103
	11th to 20th	Night	45% 6% 18% 20% 10% 1	5090
	21st to end	Night	51% 5% 9% 18% 15% 2	5588
April	1st to 10th	Night	54% 5% 11% 16% 13% 1	2200
	11th to 20th	Night	47% 6% 9% 20% 15% 2	1930
	21st to end	Night	48% 5% 10% 18% 15% 3	1890
May	1st to 10th	Night	47% 4 11% 16% 16% 6%	5264
	11th to 20th	Night	46% 6% 12% 21% 13% 2	4997
	21st to end	Night	38% 4 10% 26% 19% 2	5115
June	1st to 10th	Night	37% 6% 10% 26% 18% 2	1680
	11th to 20th	Night	37% 7% 13% 25% 16% 2	1500
	21st to end	Night	36% 7% 14% 24% 18% 1	1470
July	1st to 10th	Night	33% 3 17% 27% 17% 3	4075
	11th to 20th	Night	33% 3 10% 31% 21% 2	4812
	21st to end	Night	35% 4 10% 26% 22% 2	5606
August	1st to 10th	Night	43% 3 12% 22% 14% 5%	4124
	11th to 20th	Night	38% 4 17% 30% 11% 1	4122
	21st to end	Night	41% 4 13% 29% 12% 1	4616
September	1st to 10th	Night	36% 8% 12% 29% 14% 2	2106
	11th to 20th	Night	30% 5% 13% 30% 20% 1	2310
	21st to end	Night	43% 6% 13% 24% 14% 1	2310
October	1st to 10th	Night	35% 4 9% 28% 23% 1	4024
	11th to 20th	Night	46% 4 14% 21% 15%	3936
	21st to end	Night	45% 5% 15% 25% 9%	4279
November	1st to 10th	Night	49% 6% 13% 21% 10% 1	2690
	11th to 20th	Night	58% 8% 12% 14% 6% 1	2940
	21st to end	Night	62% 8% 14% 11% 3	2940
December	1st to 10th	Night	74% 5% 11% 8% 2	4720
	11th to 20th	Night	71% 5% 8% 11% 6%	5348
	21st to end	Night	76% 5% 8% 7% 5%	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	23% 24% 31% 14% 6% 1	248
	11th to 20th	Day	24% 20% 41% 12% 3 1	330
	21st to end	Day	26% 19% 32% 19% 4	363
February	1st to 10th	Day	27% 18% 38% 14% 3	330
	11th to 20th	Day	25% 22% 36% 15% 1	330
	21st to end	Day	29% 27% 31% 12% 1	273
March	1st to 10th	Day	26% 15% 36% 17% 5%	500
	11th to 20th	Day	25% 15% 34% 19% 5% 1	540
	21st to end	Day	27% 16% 34% 18% 5% 1	594
April	1st to 10th	Day	24% 20% 29% 19% 7% 1	540
	11th to 20th	Day	28% 17% 27% 15% 9% 3	532
	21st to end	Day	26% 12% 33% 19% 7% 1	540
May	1st to 10th	Day	21% 14% 30% 22% 10% 3	543
	11th to 20th	Day	20% 11% 28% 22% 13% 6%	567
	21st to end	Day	17% 7% 29% 26% 14% 6%	617
June	1st to 10th	Day	13% 11% 31% 28% 13% 3	570
	11th to 20th	Day	15% 10% 32% 27% 14% 2	743
	21st to end	Day	14% 7% 31% 33% 11% 3	780
July	1st to 10th	Day	9% 6% 27% 30% 20% 8%	771
	11th to 20th	Day	13% 7% 24% 28% 19% 8%	599
	21st to end	Day	11% 3 27% 32% 19% 8%	620
August	1st to 10th	Day	12% 4 20% 29% 23% 11%	566
	11th to 20th	Day	13% 4 20% 30% 19% 13%	559
	21st to end	Day	15% 6% 21% 31% 17% 10%	627
September	1st to 10th	Day	12% 8% 23% 26% 19% 12%	570
	11th to 20th	Day	11% 4 19% 26% 26% 14%	570
	21st to end	Day	17% 8% 27% 25% 15% 8%	570
October	1st to 10th	Day	19% 12% 27% 21% 14% 6%	570
	11th to 20th	Day	21% 16% 33% 22% 6% 2	542
	21st to end	Day	28% 17% 30% 21% 5% 1	563
November	1st to 10th	Day	24% 22% 29% 16% 7% 1	316
	11th to 20th	Day	25% 19% 32% 19% 4 2	220
	21st to end	Day	25% 22% 35% 15% 2	220
December	1st to 10th	Day	30% 20% 32% 13% 5%	220
	11th to 20th	Day	30% 24% 29% 14% 3	220
	21st to end	Day	33% 19% 33% 12% 2	242
January	1st to 10th	Night	22% 19% 38% 16% 5% 1	840
	11th to 20th	Night	27% 19% 32% 19% 3	840
	21st to end	Night	20% 13% 39% 23% 5%	924
February	1st to 10th	Night	21% 17% 37% 22% 2	840
	11th to 20th	Night	22% 16% 36% 21% 5%	823
	21st to end	Night	22% 17% 37% 21% 2	692
March	1st to 10th	Night	18% 16% 38% 22% 6%	840
	11th to 20th	Night	19% 18% 35% 21% 6%	840
	21st to end	Night	21% 15% 32% 23% 8% 1	924
April	1st to 10th	Night	24% 15% 32% 25% 4	840
	11th to 20th	Night	22% 15% 31% 23% 8% 1	686
	21st to end	Night	19% 12% 28% 34% 7%	630
May	1st to 10th	Night	17% 7% 33% 30% 12% 1	630
	11th to 20th	Night	20% 4 29% 34% 12% 1	539
	21st to end	Night	13% 4 29% 36% 16%	455
June	1st to 10th	Night	13% 4 30% 39% 13% 1	420
	11th to 20th	Night	12% 6% 32% 39% 11%	420
	21st to end	Night	14% 4 28% 41% 13%	420
July	1st to 10th	Night	5% 2 20% 52% 20%	410
	11th to 20th	Night	9% 4 24% 40% 22% 1	505
	21st to end	Night	10% 2 22% 45% 20% 1	690
August	1st to 10th	Night	11% 2 18% 40% 27% 2	627
	11th to 20th	Night	8% 3 19% 40% 27% 4	624
	21st to end	Night	13% 3 23% 33% 26% 2	725
September	1st to 10th	Night	11% 6% 23% 34% 23% 4	840
	11th to 20th	Night	11% 4 20% 34% 26% 5%	840
	21st to end	Night	18% 7% 22% 32% 17% 5%	840
October	1st to 10th	Night	19% 7% 28% 28% 16% 2	840
	11th to 20th	Night	21% 13% 28% 27% 9% 1	813
	21st to end	Night	26% 13% 30% 26% 5%	880
November	1st to 10th	Night	22% 12% 28% 28% 9% 1	820
	11th to 20th	Night	23% 15% 33% 20% 7% 1	840
	21st to end	Night	26% 15% 33% 21% 4	840
December	1st to 10th	Night	26% 18% 33% 18% 4	840
	11th to 20th	Night	21% 22% 36% 17% 3	840
	21st to end	Night	29% 17% 34% 17% 3	924

Page generated at 2026-10-11 05:06:29. Version ac07

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