Hawkins Pond Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Hawkins Pond Observatory clear sky chart from 2005-11-06 to 2026-09-14.

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	17% 7% 2 7% 5% 5% 5% 4 6% 8% 35%	148988
	Night	17% 8% 3 7% 5% 4 5% 4 6% 7% 36%	142107
Transparency	Day	45% 7% 13% 21% 13% 2	152497
	Night	45% 6% 12% 21% 13% 2	146687
Seeing	Day	23% 17% 28% 20% 9% 3	17251
	Night	22% 15% 27% 26% 9% 1	26052

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% 10% 4 11% 6% 6% 5% 4 5% 7% 31%	4661
	11th to 20th	Day	12% 10% 4 9% 5% 5% 5% 4 6% 7% 32%	4650
	21st to end	Day	10% 9% 3 7% 5% 5% 6% 4 6% 6% 38%	5124
February	1st to 10th	Day	14% 9% 3 7% 6% 5% 5% 5% 5% 7% 34%	1864
	11th to 20th	Day	10% 9% 3 8% 6% 5% 5% 4 6% 7% 35%	2048
	21st to end	Day	15% 11% 3 8% 5% 5% 5% 4 5% 5% 34%	1730
March	1st to 10th	Day	19% 11% 3 10% 5% 5% 5% 3 4 5% 30%	4576
	11th to 20th	Day	17% 9% 3 8% 4 5% 5% 4 5% 5% 34%	4847
	21st to end	Day	24% 9% 3 6% 4 4 3 3 5% 7% 32%	5953
April	1st to 10th	Day	19% 11% 3 7% 4 4 4 3 5% 7% 34%	2520
	11th to 20th	Day	18% 7% 3 5% 5% 4 5% 4 5% 7% 37%	2524
	21st to end	Day	21% 8% 2 7% 5% 5% 4 4 5% 6% 34%	2730
May	1st to 10th	Day	29% 8% 3 7% 4 5% 5% 4 6% 6% 24%	7639
	11th to 20th	Day	19% 7% 3 7% 5% 5% 5% 4 6% 9% 30%	8018
	21st to end	Day	20% 7% 3 6% 5% 4 5% 4 7% 8% 31%	9060
June	1st to 10th	Day	19% 6% 3 6% 4 5% 5% 5% 7% 9% 30%	2940
	11th to 20th	Day	16% 6% 2 6% 6% 5% 4 5% 7% 8% 36%	2940
	21st to end	Day	18% 7% 2 6% 5% 5% 6% 4 6% 8% 32%	2940
July	1st to 10th	Day	14% 6% 2 6% 5% 4 5% 5% 7% 10% 35%	8280
	11th to 20th	Day	10% 5% 2 6% 4 4 5% 5% 7% 9% 43%	8280
	21st to end	Day	16% 6% 2 5% 4 4 4 4 6% 8% 42%	8993
August	1st to 10th	Day	13% 6% 3 7% 5% 6% 5% 5% 7% 8% 35%	6233
	11th to 20th	Day	16% 6% 2 5% 4 4 5% 4 7% 10% 36%	5933
	21st to end	Day	11% 4 2 5% 4 5% 5% 4 7% 10% 43%	6080
September	1st to 10th	Day	12% 4 1 5% 4 4 4 4 6% 9% 46%	2520
	11th to 20th	Day	14% 4 1 4 3 3 4 3 4 5% 53%	2249
	21st to end	Day	16% 6% 1 4 4 5% 4 3 5% 7% 46%	2200
October	1st to 10th	Day	21% 6% 3 5% 4 4 5% 3 5% 5% 39%	2200
	11th to 20th	Day	17% 7% 2 5% 4 5% 5% 4 5% 7% 41%	1909
	21st to end	Day	24% 8% 3 6% 3 4 4 4 4 6% 33%	1980
November	1st to 10th	Day	14% 6% 2 6% 5% 4 4 4 5% 8% 41%	1851
	11th to 20th	Day	17% 6% 2 6% 5% 3 5% 4 7% 7% 39%	1890
	21st to end	Day	21% 7% 2 6% 5% 4 5% 4 6% 6% 35%	1832
December	1st to 10th	Day	16% 9% 4 10% 6% 5% 6% 5% 7% 7% 27%	2680
	11th to 20th	Day	20% 8% 2 6% 3 3 4 4 5% 6% 38%	3066
	21st to end	Day	21% 10% 3 6% 5% 4 4 3 4 5% 34%	4048
January	1st to 10th	Night	12% 9% 4 11% 7% 5% 5% 3 4 6% 34%	8234
	11th to 20th	Night	12% 11% 5% 11% 7% 6% 6% 4 6% 6% 25%	8235
	21st to end	Night	11% 8% 3 8% 5% 5% 6% 5% 6% 7% 35%	9057
February	1st to 10th	Night	13% 9% 3 7% 5% 5% 5% 5% 6% 7% 35%	2751
	11th to 20th	Night	10% 9% 3 7% 5% 4 6% 5% 7% 8% 36%	2458
	21st to end	Night	14% 8% 3 7% 5% 5% 4 3 6% 8% 36%	2076
March	1st to 10th	Night	22% 9% 2 7% 4 5% 5% 4 6% 6% 30%	5484
	11th to 20th	Night	16% 10% 3 8% 6% 5% 5% 4 5% 6% 33%	5331
	21st to end	Night	25% 9% 3 6% 3 4 4 3 5% 7% 32%	5218
April	1st to 10th	Night	21% 8% 3 7% 4 4 4 4 5% 6% 35%	2100
	11th to 20th	Night	20% 7% 3 6% 5% 4 4 3 6% 6% 36%	2044
	21st to end	Night	20% 7% 3 5% 4 4 4 3 5% 7% 38%	1890
May	1st to 10th	Night	32% 8% 3 6% 5% 4 4 3 5% 6% 24%	5259
	11th to 20th	Night	17% 9% 3 8% 5% 5% 5% 5% 5% 7% 31%	4885
	21st to end	Night	21% 6% 2 6% 4 5% 5% 4 6% 7% 35%	5114
June	1st to 10th	Night	19% 7% 3 6% 4 4 5% 4 6% 7% 36%	1680
	11th to 20th	Night	18% 6% 2 6% 4 5% 4 4 6% 7% 37%	1680
	21st to end	Night	18% 5% 3 6% 5% 4 4 4 6% 8% 37%	1680
July	1st to 10th	Night	13% 6% 2 6% 4 5% 5% 5% 7% 10% 38%	4680
	11th to 20th	Night	13% 5% 2 7% 4 5% 4 4 6% 7% 44%	4680
	21st to end	Night	15% 4 1 4 3 3 4 4 6% 7% 48%	5084
August	1st to 10th	Night	17% 7% 3 8% 5% 5% 5% 3 6% 6% 36%	3868
	11th to 20th	Night	16% 8% 2 6% 4 4 4 3 6% 8% 39%	4109
	21st to end	Night	12% 4 2 5% 4 4 5% 4 7% 9% 46%	5045
September	1st to 10th	Night	12% 5% 2 5% 4 4 3 3 6% 6% 51%	2100
	11th to 20th	Night	13% 5% 1 5% 3 3 3 3 5% 6% 52%	2218
	21st to end	Night	16% 5% 2 5% 3 4 5% 3 6% 6% 44%	2200
October	1st to 10th	Night	20% 7% 2 6% 4 4 5% 3 5% 6% 40%	2200
	11th to 20th	Night	16% 7% 2 6% 5% 5% 4 4 6% 8% 39%	2486
	21st to end	Night	23% 8% 2 6% 4 4 4 3 6% 6% 35%	2860
November	1st to 10th	Night	15% 6% 2 6% 4 4 4 4 5% 7% 43%	2667
	11th to 20th	Night	16% 7% 2 7% 5% 4 4 4 5% 7% 41%	2730
	21st to end	Night	16% 7% 2 6% 5% 5% 5% 4 6% 7% 37%	2786
December	1st to 10th	Night	16% 10% 3 9% 6% 5% 5% 4 6% 7% 29%	4720
	11th to 20th	Night	23% 8% 2 6% 4 4 4 3 5% 6% 35%	5348
	21st to end	Night	21% 11% 3 7% 5% 4 4 3 4 5% 34%	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	49% 5% 13% 22% 11%	4662
	11th to 20th	Day	46% 6% 12% 19% 14% 2	4680
	21st to end	Day	40% 8% 10% 23% 16% 3	5124
February	1st to 10th	Day	48% 7% 11% 20% 11% 2	1864
	11th to 20th	Day	46% 6% 12% 20% 13% 3	2057
	21st to end	Day	50% 6% 12% 18% 13% 2	1730
March	1st to 10th	Day	55% 5% 9% 14% 11% 7%	4579
	11th to 20th	Day	49% 6% 15% 17% 11% 3	4847
	21st to end	Day	51% 4 7% 17% 17% 4	5953
April	1st to 10th	Day	50% 5% 9% 18% 14% 4	2520
	11th to 20th	Day	45% 7% 11% 19% 16% 2	2524
	21st to end	Day	51% 4 9% 18% 15% 3	2730
May	1st to 10th	Day	57% 8% 10% 15% 9% 1	7651
	11th to 20th	Day	48% 8% 15% 18% 10% 1	8022
	21st to end	Day	47% 7% 13% 21% 11% 1	9061
June	1st to 10th	Day	49% 7% 12% 21% 11%	2940
	11th to 20th	Day	44% 7% 12% 19% 15% 3	2940
	21st to end	Day	47% 9% 12% 19% 12% 1	2940
July	1st to 10th	Day	42% 7% 16% 22% 13%	8210
	11th to 20th	Day	35% 7% 14% 29% 14% 1	8205
	21st to end	Day	39% 5% 13% 28% 15% 1	8795
August	1st to 10th	Day	44% 8% 18% 18% 11% 1	6219
	11th to 20th	Day	40% 8% 18% 25% 8% 1	5972
	21st to end	Day	34% 7% 17% 25% 17% 1	6080
September	1st to 10th	Day	33% 7% 13% 29% 16% 1	2520
	11th to 20th	Day	33% 5% 10% 28% 22% 2	2249
	21st to end	Day	37% 6% 12% 25% 17% 2	2200
October	1st to 10th	Day	44% 8% 9% 22% 16% 1	3590
	11th to 20th	Day	39% 5% 14% 25% 14% 3	3086
	21st to end	Day	38% 5% 9% 28% 16% 3	3180
November	1st to 10th	Day	39% 6% 16% 23% 15% 2	1851
	11th to 20th	Day	41% 5% 14% 18% 19% 3	1890
	21st to end	Day	48% 7% 17% 19% 9% 1	1832
December	1st to 10th	Day	51% 7% 15% 19% 7% 1	2680
	11th to 20th	Day	46% 5% 10% 17% 19% 3	3066
	21st to end	Day	53% 5% 7% 17% 14% 5%	4048
January	1st to 10th	Night	49% 5% 14% 20% 11% 1	8234
	11th to 20th	Night	53% 6% 14% 14% 11% 3	8280
	21st to end	Night	43% 6% 9% 20% 17% 4	9057
February	1st to 10th	Night	46% 7% 11% 21% 13% 2	2751
	11th to 20th	Night	43% 7% 12% 22% 14% 2	2460
	21st to end	Night	44% 6% 11% 23% 12% 4	2076
March	1st to 10th	Night	52% 5% 10% 15% 14% 4	5494
	11th to 20th	Night	50% 6% 15% 15% 11% 2	5332
	21st to end	Night	52% 4 7% 14% 20% 4	5218
April	1st to 10th	Night	49% 5% 10% 18% 16% 2	2100
	11th to 20th	Night	49% 5% 9% 21% 16% 1	2044
	21st to end	Night	47% 5% 11% 18% 17% 3	1890
May	1st to 10th	Night	60% 6% 10% 14% 9% 1	5265
	11th to 20th	Night	49% 8% 12% 21% 9% 1	4886
	21st to end	Night	47% 7% 13% 23% 9% 1	5115
June	1st to 10th	Night	47% 7% 12% 21% 13%	1680
	11th to 20th	Night	45% 8% 14% 19% 12% 2	1680
	21st to end	Night	43% 9% 14% 22% 10% 1	1680
July	1st to 10th	Night	40% 8% 18% 23% 12%	4640
	11th to 20th	Night	37% 7% 13% 25% 17%	4632
	21st to end	Night	35% 6% 14% 33% 12%	4967
August	1st to 10th	Night	48% 8% 14% 19% 10% 1	3858
	11th to 20th	Night	41% 8% 16% 25% 10%	4136
	21st to end	Night	33% 7% 19% 27% 14%	5045
September	1st to 10th	Night	33% 7% 13% 29% 17%	2100
	11th to 20th	Night	33% 6% 11% 28% 22% 1	2218
	21st to end	Night	39% 7% 11% 26% 16% 1	2200
October	1st to 10th	Night	42% 7% 14% 23% 13% 1	3590
	11th to 20th	Night	35% 6% 14% 26% 18% 3	4048
	21st to end	Night	40% 5% 10% 29% 14% 2	4610
November	1st to 10th	Night	40% 7% 12% 24% 16% 2	2667
	11th to 20th	Night	42% 5% 12% 22% 16% 2	2730
	21st to end	Night	45% 7% 16% 21% 9% 1	2786
December	1st to 10th	Night	50% 7% 13% 23% 6%	4720
	11th to 20th	Night	49% 5% 12% 14% 18% 2	5348
	21st to end	Night	53% 4 10% 18% 13% 3	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	28% 23% 30% 16% 3	220
	11th to 20th	Day	31% 22% 29% 14% 3 1	220
	21st to end	Day	22% 26% 27% 19% 5%	242
February	1st to 10th	Day	29% 24% 28% 15% 4	356
	11th to 20th	Day	25% 27% 32% 13% 3	536
	21st to end	Day	28% 24% 28% 17% 2	446
March	1st to 10th	Day	30% 19% 32% 16% 4	540
	11th to 20th	Day	30% 26% 25% 13% 5% 1	540
	21st to end	Day	29% 24% 25% 14% 5% 2	594
April	1st to 10th	Day	32% 21% 25% 14% 5% 2	540
	11th to 20th	Day	31% 23% 23% 16% 6% 2	532
	21st to end	Day	30% 20% 27% 14% 7% 2	540
May	1st to 10th	Day	32% 21% 26% 15% 5% 2	543
	11th to 20th	Day	23% 18% 32% 20% 6% 2	567
	21st to end	Day	22% 13% 34% 20% 8% 2	617
June	1st to 10th	Day	19% 13% 36% 20% 12% 1	570
	11th to 20th	Day	18% 16% 32% 20% 11% 3	570
	21st to end	Day	19% 14% 32% 21% 11% 3	570
July	1st to 10th	Day	17% 10% 31% 25% 13% 4	565
	11th to 20th	Day	16% 8% 29% 31% 13% 3	564
	21st to end	Day	15% 10% 34% 25% 12% 5%	620
August	1st to 10th	Day	12% 11% 25% 29% 18% 4	566
	11th to 20th	Day	16% 11% 28% 21% 17% 7%	559
	21st to end	Day	13% 10% 28% 29% 15% 5%	627
September	1st to 10th	Day	16% 12% 26% 23% 17% 6%	570
	11th to 20th	Day	16% 10% 25% 21% 17% 11%	542
	21st to end	Day	15% 16% 27% 22% 13% 6%	530
October	1st to 10th	Day	25% 15% 21% 21% 14% 5%	530
	11th to 20th	Day	23% 17% 23% 22% 12% 2	464
	21st to end	Day	37% 14% 23% 20% 6% 1	462
November	1st to 10th	Day	26% 15% 28% 22% 8% 1	425
	11th to 20th	Day	30% 20% 24% 19% 6% 1	430
	21st to end	Day	32% 22% 26% 15% 5% 1	372
December	1st to 10th	Day	26% 22% 28% 19% 5%	220
	11th to 20th	Day	32% 22% 31% 11% 3	220
	21st to end	Day	30% 20% 28% 15% 6%	242
January	1st to 10th	Night	21% 23% 31% 23% 3	840
	11th to 20th	Night	28% 18% 27% 23% 3	840
	21st to end	Night	19% 23% 33% 22% 4	924
February	1st to 10th	Night	21% 20% 33% 23% 2	840
	11th to 20th	Night	21% 23% 33% 20% 3	823
	21st to end	Night	21% 21% 32% 22% 4	692
March	1st to 10th	Night	28% 16% 30% 23% 3	840
	11th to 20th	Night	24% 20% 27% 23% 5%	840
	21st to end	Night	25% 20% 28% 20% 7%	924
April	1st to 10th	Night	27% 17% 29% 23% 4	840
	11th to 20th	Night	25% 18% 29% 23% 7%	800
	21st to end	Night	24% 16% 29% 25% 6%	630
May	1st to 10th	Night	28% 12% 25% 27% 7%	630
	11th to 20th	Night	20% 13% 30% 28% 9%	506
	21st to end	Night	20% 10% 22% 36% 11% 1	455
June	1st to 10th	Night	19% 8% 25% 35% 11% 1	420
	11th to 20th	Night	20% 9% 26% 30% 14%	420
	21st to end	Night	20% 5% 24% 40% 11%	420
July	1st to 10th	Night	13% 5% 22% 43% 16%	410
	11th to 20th	Night	15% 4 21% 40% 19% 2	408
	21st to end	Night	16% 4 21% 40% 18% 2	460
August	1st to 10th	Night	17% 4 20% 39% 20% 1	503
	11th to 20th	Night	16% 8% 26% 30% 17% 3	626
	21st to end	Night	15% 6% 22% 33% 21% 3	924
September	1st to 10th	Night	13% 8% 27% 31% 19% 2	840
	11th to 20th	Night	15% 8% 22% 30% 19% 6%	813
	21st to end	Night	19% 10% 22% 30% 17% 2	800
October	1st to 10th	Night	24% 11% 19% 28% 16% 2	800
	11th to 20th	Night	20% 16% 27% 24% 12% 1	800
	21st to end	Night	28% 15% 23% 26% 8%	880
November	1st to 10th	Night	19% 17% 28% 27% 8% 1	820
	11th to 20th	Night	22% 21% 26% 23% 7% 1	840
	21st to end	Night	23% 20% 28% 24% 5%	840
December	1st to 10th	Night	26% 21% 29% 20% 5%	840
	11th to 20th	Night	27% 21% 28% 20% 3	840
	21st to end	Night	28% 21% 25% 23% 3	924

Page generated at 2026-09-11 04:11:55. Version ac07

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