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 2025-05-11.

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% 8% 3 7% 5% 5% 5% 4 6% 7% 35%	113549
	Night	17% 8% 3 7% 5% 4 4 4 6% 7% 36%	115398
Transparency	Day	45% 7% 12% 20% 13% 2	117104
	Night	46% 6% 12% 20% 13% 2	120007
Seeing	Day	24% 17% 28% 20% 9% 3	15472
	Night	22% 15% 27% 26% 9% 1	24483

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	13% 10% 4 10% 6% 5% 4 4 5% 6% 32%	3597
	11th to 20th	Day	12% 9% 5% 10% 5% 4 5% 4 6% 7% 33%	3570
	21st to end	Day	12% 9% 3 8% 5% 4 5% 4 6% 6% 38%	3960
February	1st to 10th	Day	14% 9% 3 7% 6% 6% 5% 5% 5% 7% 33%	1775
	11th to 20th	Day	11% 9% 3 8% 7% 5% 5% 4 5% 7% 35%	1948
	21st to end	Day	15% 11% 3 8% 5% 5% 5% 3 5% 5% 34%	1650
March	1st to 10th	Day	19% 11% 3 10% 5% 5% 5% 3 4 4 30%	4476
	11th to 20th	Day	17% 9% 3 8% 4 5% 5% 4 5% 5% 34%	4742
	21st to end	Day	24% 9% 3 6% 4 4 3 3 5% 7% 32%	5824
April	1st to 10th	Day	19% 11% 3 7% 4 4 4 3 5% 7% 34%	2400
	11th to 20th	Day	18% 7% 2 5% 5% 4 4 4 5% 7% 38%	2403
	21st to end	Day	21% 8% 2 7% 5% 5% 4 4 5% 6% 33%	2600
May	1st to 10th	Day	24% 10% 3 9% 5% 5% 5% 3 5% 6% 26%	4236
	11th to 20th	Day	18% 8% 3 8% 5% 4 5% 4 6% 8% 30%	4292
	21st to end	Day	14% 5% 2 5% 4 4 5% 5% 7% 9% 39%	4837
June	1st to 10th	Day	20% 6% 2 6% 4 5% 6% 5% 7% 8% 30%	2660
	11th to 20th	Day	16% 6% 2 6% 6% 5% 5% 5% 7% 8% 37%	2660
	21st to end	Day	18% 8% 2 6% 6% 5% 6% 5% 6% 8% 30%	2660
July	1st to 10th	Day	14% 6% 2 6% 5% 5% 6% 5% 7% 9% 36%	4440
	11th to 20th	Day	11% 5% 2 6% 5% 5% 6% 6% 8% 10% 37%	4440
	21st to end	Day	19% 6% 2 6% 5% 4 5% 4 6% 7% 37%	4814
August	1st to 10th	Day	14% 6% 3 6% 5% 6% 5% 5% 6% 8% 35%	4248
	11th to 20th	Day	17% 7% 2 7% 5% 4 5% 5% 7% 10% 31%	4026
	21st to end	Day	10% 3 2 5% 4 5% 5% 4 6% 11% 44%	4180
September	1st to 10th	Day	12% 3 1 6% 4 4 5% 4 6% 9% 46%	2280
	11th to 20th	Day	14% 4 1 5% 3 4 4 3 4 6% 52%	2104
	21st to end	Day	16% 6% 1 4 4 5% 4 3 5% 6% 45%	2090
October	1st to 10th	Day	22% 7% 3 6% 4 5% 5% 3 5% 5% 36%	2090
	11th to 20th	Day	16% 7% 2 5% 4 5% 5% 4 5% 7% 41%	1814
	21st to end	Day	25% 8% 3 5% 3 4 4 4 4 6% 33%	1881
November	1st to 10th	Day	14% 6% 2 6% 5% 4 4 3 5% 9% 42%	1761
	11th to 20th	Day	18% 6% 1 5% 5% 3 5% 4 7% 7% 40%	1800
	21st to end	Day	21% 7% 2 6% 4 3 4 4 6% 6% 36%	1745
December	1st to 10th	Day	16% 9% 4 10% 5% 5% 6% 5% 7% 7% 26%	2600
	11th to 20th	Day	20% 8% 2 5% 3 3 4 4 5% 7% 38%	2986
	21st to end	Day	21% 10% 3 6% 4 4 4 3 4 5% 34%	3960
January	1st to 10th	Night	13% 9% 4 11% 7% 5% 5% 3 5% 6% 33%	6349
	11th to 20th	Night	11% 10% 4 11% 7% 6% 6% 5% 6% 7% 27%	6315
	21st to end	Night	13% 9% 3 9% 5% 5% 5% 4 5% 6% 35%	6996
February	1st to 10th	Night	14% 9% 3 7% 5% 5% 5% 5% 6% 7% 34%	2620
	11th to 20th	Night	10% 9% 3 7% 5% 4 6% 5% 7% 8% 36%	2338
	21st to end	Night	14% 8% 3 7% 5% 5% 4 3 6% 8% 36%	1980
March	1st to 10th	Night	22% 9% 2 7% 4 5% 5% 4 6% 6% 30%	5364
	11th to 20th	Night	16% 10% 3 8% 6% 5% 5% 4 5% 6% 33%	5216
	21st to end	Night	25% 9% 3 6% 3 4 4 3 5% 6% 32%	5105
April	1st to 10th	Night	21% 8% 3 7% 5% 4 4 4 5% 6% 35%	2000
	11th to 20th	Night	20% 7% 3 6% 5% 4 4 3 6% 6% 36%	1945
	21st to end	Night	21% 7% 2 5% 4 4 4 3 5% 7% 38%	1800
May	1st to 10th	Night	28% 10% 3 6% 5% 4 4 4 5% 5% 24%	2924
	11th to 20th	Night	18% 10% 3 9% 6% 5% 5% 5% 6% 7% 27%	2638
	21st to end	Night	15% 5% 2 6% 4 4 4 4 6% 7% 41%	2738
June	1st to 10th	Night	20% 7% 3 6% 4 4 5% 4 6% 7% 34%	1520
	11th to 20th	Night	19% 6% 2 6% 4 5% 4 4 6% 7% 38%	1520
	21st to end	Night	18% 6% 3 7% 5% 4 5% 4 5% 7% 36%	1520
July	1st to 10th	Night	12% 5% 2 6% 5% 5% 5% 5% 8% 10% 38%	2520
	11th to 20th	Night	15% 6% 2 7% 3 4 3 4 6% 8% 43%	2520
	21st to end	Night	17% 6% 2 5% 4 4 4 4 6% 7% 41%	2739
August	1st to 10th	Night	22% 7% 3 7% 4 4 4 3 5% 6% 35%	2648
	11th to 20th	Night	16% 8% 2 6% 4 4 5% 3 7% 8% 36%	2799
	21st to end	Night	10% 4 2 5% 4 4 4 4 6% 9% 48%	3476
September	1st to 10th	Night	11% 5% 2 5% 4 3 3 3 5% 6% 52%	1900
	11th to 20th	Night	14% 5% 1 5% 3 3 3 3 5% 6% 51%	2076
	21st to end	Night	16% 5% 2 5% 3 4 4 3 6% 6% 44%	2090
October	1st to 10th	Night	21% 7% 2 6% 4 4 5% 3 5% 6% 38%	2090
	11th to 20th	Night	16% 7% 2 6% 5% 5% 4 4 6% 8% 38%	2361
	21st to end	Night	23% 8% 2 6% 4 4 4 3 6% 6% 34%	2717
November	1st to 10th	Night	15% 6% 2 6% 4 4 5% 4 5% 7% 43%	2537
	11th to 20th	Night	16% 7% 2 6% 5% 4 4 4 5% 7% 41%	2600
	21st to end	Night	17% 7% 2 6% 5% 4 5% 4 6% 7% 38%	2653
December	1st to 10th	Night	17% 10% 3 9% 6% 5% 5% 4 6% 7% 29%	4580
	11th to 20th	Night	23% 9% 2 5% 4 3 4 3 5% 6% 35%	5208
	21st to end	Night	21% 11% 3 7% 4 4 4 3 4 5% 34%	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	50% 5% 11% 22% 11%	3598
	11th to 20th	Day	45% 7% 14% 20% 12% 3	3600
	21st to end	Day	43% 8% 9% 20% 17% 3	3960
February	1st to 10th	Day	49% 7% 11% 19% 10% 3	1775
	11th to 20th	Day	47% 6% 12% 19% 13% 3	1957
	21st to end	Day	50% 6% 12% 18% 13% 2	1650
March	1st to 10th	Day	55% 5% 9% 14% 10% 7%	4479
	11th to 20th	Day	49% 6% 15% 17% 11% 3	4742
	21st to end	Day	51% 4 7% 17% 17% 4	5824
April	1st to 10th	Day	50% 5% 9% 19% 14% 4	2400
	11th to 20th	Day	44% 7% 11% 19% 16% 2	2403
	21st to end	Day	52% 4 9% 18% 14% 3	2600
May	1st to 10th	Day	57% 8% 9% 17% 8% 1	4250
	11th to 20th	Day	49% 10% 15% 16% 9% 1	4296
	21st to end	Day	37% 9% 15% 24% 15% 1	4837
June	1st to 10th	Day	49% 8% 12% 20% 10%	2660
	11th to 20th	Day	44% 7% 12% 20% 15% 3	2660
	21st to end	Day	49% 9% 11% 18% 12% 1	2660
July	1st to 10th	Day	41% 8% 14% 22% 15% 1	4370
	11th to 20th	Day	38% 9% 16% 26% 11% 1	4365
	21st to end	Day	45% 6% 13% 21% 14% 1	4661
August	1st to 10th	Day	44% 9% 15% 22% 11%	4234
	11th to 20th	Day	45% 9% 16% 22% 7%	4065
	21st to end	Day	32% 8% 17% 26% 17% 1	4180
September	1st to 10th	Day	33% 8% 14% 28% 16% 1	2280
	11th to 20th	Day	34% 5% 11% 28% 21% 2	2104
	21st to end	Day	38% 6% 12% 25% 17% 2	2090
October	1st to 10th	Day	45% 8% 9% 21% 16% 1	3480
	11th to 20th	Day	39% 5% 14% 24% 15% 3	2991
	21st to end	Day	38% 5% 9% 28% 17% 3	3081
November	1st to 10th	Day	39% 6% 16% 23% 15% 2	1761
	11th to 20th	Day	41% 5% 14% 18% 20% 3	1800
	21st to end	Day	47% 7% 17% 19% 9% 1	1745
December	1st to 10th	Day	51% 7% 16% 19% 6% 1	2600
	11th to 20th	Day	46% 5% 10% 17% 19% 3	2986
	21st to end	Day	53% 5% 7% 17% 14% 5%	3960
January	1st to 10th	Night	49% 5% 13% 21% 11% 1	6349
	11th to 20th	Night	52% 6% 15% 16% 9% 2	6360
	21st to end	Night	45% 7% 10% 17% 17% 4	6996
February	1st to 10th	Night	47% 7% 12% 20% 13% 2	2620
	11th to 20th	Night	43% 7% 12% 21% 15% 2	2340
	21st to end	Night	44% 7% 11% 23% 12% 4	1980
March	1st to 10th	Night	52% 5% 10% 14% 14% 4	5374
	11th to 20th	Night	50% 6% 16% 15% 11% 2	5217
	21st to end	Night	52% 3 7% 14% 20% 4	5105
April	1st to 10th	Night	49% 5% 10% 18% 15% 2	2000
	11th to 20th	Night	49% 5% 9% 21% 16% 1	1945
	21st to end	Night	47% 5% 11% 18% 16% 3	1800
May	1st to 10th	Night	59% 7% 9% 16% 8% 1	2930
	11th to 20th	Night	53% 10% 12% 15% 8% 2	2639
	21st to end	Night	40% 8% 17% 20% 13% 2	2739
June	1st to 10th	Night	48% 8% 13% 19% 12%	1520
	11th to 20th	Night	45% 7% 14% 18% 13% 2	1520
	21st to end	Night	44% 10% 14% 21% 10% 1	1520
July	1st to 10th	Night	38% 10% 17% 21% 14%	2480
	11th to 20th	Night	39% 8% 15% 24% 15%	2472
	21st to end	Night	41% 6% 11% 28% 13% 1	2651
August	1st to 10th	Night	51% 7% 11% 21% 9%	2638
	11th to 20th	Night	43% 9% 17% 20% 11%	2826
	21st to end	Night	30% 8% 19% 28% 15% 1	3476
September	1st to 10th	Night	33% 7% 13% 30% 17% 1	1900
	11th to 20th	Night	34% 6% 11% 28% 20% 1	2076
	21st to end	Night	38% 6% 12% 27% 16% 1	2090
October	1st to 10th	Night	43% 7% 14% 23% 12% 1	3480
	11th to 20th	Night	35% 6% 13% 25% 18% 3	3923
	21st to end	Night	40% 5% 10% 29% 15% 2	4467
November	1st to 10th	Night	39% 7% 12% 24% 15% 2	2537
	11th to 20th	Night	42% 5% 12% 22% 17% 2	2600
	21st to end	Night	45% 7% 16% 22% 9% 1	2653
December	1st to 10th	Night	51% 7% 13% 23% 6%	4580
	11th to 20th	Night	49% 5% 12% 13% 18% 2	5208
	21st to end	Night	53% 4 10% 18% 13% 2	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	31% 22% 29% 16% 3 1	200
	11th to 20th	Day	32% 22% 29% 14% 3 2	200
	21st to end	Day	20% 25% 29% 20% 5%	220
February	1st to 10th	Day	31% 25% 27% 15% 3	327
	11th to 20th	Day	27% 27% 31% 12% 3	496
	21st to end	Day	29% 24% 27% 17% 2	414
March	1st to 10th	Day	30% 19% 32% 15% 4	500
	11th to 20th	Day	29% 26% 26% 13% 5% 1	500
	21st to end	Day	28% 23% 26% 15% 5% 2	550
April	1st to 10th	Day	32% 22% 25% 14% 6% 2	500
	11th to 20th	Day	31% 24% 22% 16% 6% 2	492
	21st to end	Day	30% 21% 27% 14% 6% 2	500
May	1st to 10th	Day	31% 20% 25% 16% 5% 2	503
	11th to 20th	Day	22% 17% 32% 21% 7% 2	487
	21st to end	Day	21% 12% 34% 22% 9% 3	529
June	1st to 10th	Day	19% 13% 37% 18% 12% 2	490
	11th to 20th	Day	17% 16% 31% 22% 12% 3	490
	21st to end	Day	20% 14% 32% 20% 11% 3	490
July	1st to 10th	Day	17% 10% 31% 25% 13% 4	485
	11th to 20th	Day	15% 8% 30% 32% 13% 3	484
	21st to end	Day	14% 10% 35% 26% 11% 3	532
August	1st to 10th	Day	12% 12% 27% 28% 17% 4	486
	11th to 20th	Day	18% 11% 27% 21% 17% 6%	479
	21st to end	Day	13% 10% 27% 28% 16% 6%	539
September	1st to 10th	Day	15% 12% 26% 22% 18% 8%	490
	11th to 20th	Day	17% 11% 24% 21% 16% 11%	490
	21st to end	Day	15% 17% 26% 23% 13% 6%	490
October	1st to 10th	Day	26% 14% 21% 21% 14% 4	490
	11th to 20th	Day	23% 18% 23% 23% 12% 2	430
	21st to end	Day	38% 14% 22% 20% 6% 1	429
November	1st to 10th	Day	25% 14% 27% 24% 9% 1	395
	11th to 20th	Day	30% 20% 24% 20% 7% 1	400
	21st to end	Day	32% 22% 25% 15% 5% 1	345
December	1st to 10th	Day	25% 24% 28% 19% 5%	200
	11th to 20th	Day	34% 21% 31% 12% 4	200
	21st to end	Day	29% 20% 28% 15% 7%	220
January	1st to 10th	Night	21% 22% 31% 23% 3	800
	11th to 20th	Night	27% 18% 27% 24% 3	800
	21st to end	Night	18% 22% 33% 22% 4	880
February	1st to 10th	Night	22% 20% 33% 23% 2	800
	11th to 20th	Night	21% 23% 33% 19% 3	783
	21st to end	Night	21% 21% 32% 21% 5%	660
March	1st to 10th	Night	28% 16% 30% 23% 3	800
	11th to 20th	Night	23% 21% 28% 24% 5% 1	800
	21st to end	Night	25% 19% 28% 21% 7%	880
April	1st to 10th	Night	26% 17% 29% 23% 4	800
	11th to 20th	Night	24% 17% 29% 23% 7%	761
	21st to end	Night	25% 16% 29% 24% 6%	600
May	1st to 10th	Night	28% 12% 25% 27% 8%	600
	11th to 20th	Night	21% 12% 29% 29% 10%	461
	21st to end	Night	19% 10% 21% 37% 12% 1	411
June	1st to 10th	Night	20% 8% 26% 34% 11% 2	380
	11th to 20th	Night	20% 8% 25% 31% 15% 1	380
	21st to end	Night	21% 5% 24% 38% 12% 1	380
July	1st to 10th	Night	14% 5% 22% 42% 16%	370
	11th to 20th	Night	16% 2 21% 39% 20% 2	368
	21st to end	Night	16% 4 20% 40% 17% 2	416
August	1st to 10th	Night	17% 4 21% 39% 19%	455
	11th to 20th	Night	17% 7% 27% 30% 17% 3	566
	21st to end	Night	16% 5% 21% 33% 21% 3	836
September	1st to 10th	Night	13% 7% 27% 31% 20% 2	760
	11th to 20th	Night	16% 8% 22% 29% 19% 6%	760
	21st to end	Night	19% 10% 22% 29% 17% 2	760
October	1st to 10th	Night	24% 11% 19% 29% 15% 2	760
	11th to 20th	Night	20% 16% 26% 24% 13% 1	760
	21st to end	Night	28% 16% 23% 25% 8%	836
November	1st to 10th	Night	18% 17% 28% 28% 9% 1	780
	11th to 20th	Night	22% 21% 26% 23% 7% 1	800
	21st to end	Night	23% 20% 28% 23% 5% 1	800
December	1st to 10th	Night	26% 21% 29% 19% 5%	800
	11th to 20th	Night	27% 21% 28% 21% 4	800
	21st to end	Night	28% 21% 25% 23% 3	880

Page generated at 2025-05-08 09:33:57. Version ac07

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