Blueberry Pond Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Blueberry Pond Observatory clear sky chart from 2005-11-06 to 2024-11-25.

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	18% 8% 2 6% 4 4 4 4 5% 7% 38%	101150
	Night	18% 8% 3 6% 4 4 4 3 5% 6% 37%	98297
Transparency	Day	44% 5% 12% 23% 14% 2	104676
	Night	46% 4 11% 23% 14% 2	102861
Seeing	Day	22% 11% 32% 23% 9% 3	15035
	Night	22% 11% 29% 27% 10% 1	23960

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	16% 7% 2 6% 5% 4 4 3 5% 6% 42%	2517
	11th to 20th	Day	17% 7% 2 6% 4 5% 4 4 4 6% 40%	2520
	21st to end	Day	17% 12% 2 6% 3 4 4 4 5% 5% 38%	2772
February	1st to 10th	Day	18% 9% 2 7% 5% 4 4 4 6% 5% 37%	1680
	11th to 20th	Day	13% 9% 3 7% 5% 6% 5% 4 5% 5% 38%	1848
	21st to end	Day	16% 11% 3 7% 4 3 5% 3 6% 6% 36%	1570
March	1st to 10th	Day	26% 12% 3 5% 5% 4 3 3 4 5% 30%	3116
	11th to 20th	Day	16% 8% 2 6% 5% 4 4 4 5% 7% 39%	3411
	21st to end	Day	24% 9% 3 6% 4 3 3 3 5% 6% 35%	3910
April	1st to 10th	Day	20% 10% 3 8% 4 3 4 4 4 6% 35%	2280
	11th to 20th	Day	18% 6% 2 6% 4 4 5% 4 5% 6% 39%	2347
	21st to end	Day	23% 8% 2 6% 5% 3 4 3 5% 5% 35%	2470
May	1st to 10th	Day	23% 10% 3 7% 5% 4 4 4 5% 6% 27%	4106
	11th to 20th	Day	19% 8% 3 8% 5% 4 4 4 6% 8% 32%	4138
	21st to end	Day	16% 5% 2 6% 5% 5% 5% 4 7% 9% 37%	4837
June	1st to 10th	Day	21% 9% 2 6% 4 4 4 4 5% 8% 32%	2660
	11th to 20th	Day	16% 7% 2 6% 5% 4 4 4 5% 8% 39%	2660
	21st to end	Day	22% 7% 2 6% 5% 5% 4 5% 5% 7% 31%	2660
July	1st to 10th	Day	15% 6% 2 6% 5% 5% 5% 4 6% 9% 36%	4440
	11th to 20th	Day	12% 6% 2 6% 4 5% 5% 5% 7% 10% 38%	4440
	21st to end	Day	21% 6% 2 5% 4 4 4 4 6% 8% 37%	4814
August	1st to 10th	Day	16% 6% 2 8% 4 4 5% 4 6% 9% 36%	4119
	11th to 20th	Day	17% 8% 3 7% 4 4 5% 4 6% 8% 34%	4045
	21st to end	Day	9% 4 2 5% 5% 4 5% 4 7% 9% 46%	4340
September	1st to 10th	Day	12% 4 2 5% 4 4 4 4 5% 8% 49%	2237
	11th to 20th	Day	12% 6% 1 5% 3 3 3 2 4 6% 55%	2090
	21st to end	Day	17% 6% 2 5% 3 3 4 4 5% 8% 45%	2090
October	1st to 10th	Day	18% 7% 2 7% 4 4 4 3 4 6% 40%	2090
	11th to 20th	Day	17% 6% 2 6% 3 4 4 3 4 6% 43%	1832
	21st to end	Day	23% 8% 2 5% 3 3 4 2 4 5% 40%	1881
November	1st to 10th	Day	17% 6% 2 4 3 3 4 3 5% 6% 47%	1761
	11th to 20th	Day	20% 5% 1 4 3 3 4 3 6% 6% 46%	1800
	21st to end	Day	23% 8% 2 5% 3 2 3 3 3 6% 42%	1746
December	1st to 10th	Day	22% 9% 2 6% 4 4 3 4 3 5% 37%	1378
	11th to 20th	Day	23% 9% 2 5% 2 4 3 3 4 4 42%	1773
	21st to end	Day	26% 10% 2 6% 4 5% 4 4 4 6% 30%	2772
January	1st to 10th	Night	15% 9% 3 6% 4 3 3 3 5% 5% 43%	4429
	11th to 20th	Night	14% 8% 3 9% 5% 5% 4 3 5% 6% 38%	4440
	21st to end	Night	20% 11% 3 8% 5% 4 3 3 4 5% 34%	4884
February	1st to 10th	Night	17% 9% 3 7% 5% 5% 4 4 5% 6% 36%	2493
	11th to 20th	Night	13% 11% 2 6% 5% 5% 4 3 5% 5% 40%	2218
	21st to end	Night	15% 10% 3 6% 4 5% 3 3 5% 6% 40%	1884
March	1st to 10th	Night	28% 11% 2 5% 3 4 3 3 4 5% 32%	3724
	11th to 20th	Night	14% 8% 3 8% 5% 6% 6% 4 6% 7% 33%	3548
	21st to end	Night	25% 9% 3 6% 4 4 4 4 6% 6% 30%	3706
April	1st to 10th	Night	22% 10% 2 5% 4 4 4 3 5% 6% 36%	1900
	11th to 20th	Night	19% 6% 2 6% 4 4 5% 4 5% 6% 38%	1780
	21st to end	Night	22% 7% 2 6% 5% 4 4 4 4 6% 36%	1710
May	1st to 10th	Night	23% 8% 3 7% 4 4 5% 4 6% 8% 28%	2834
	11th to 20th	Night	17% 9% 3 8% 6% 5% 6% 5% 7% 9% 26%	2783
	21st to end	Night	16% 8% 3 8% 4 4 5% 3 6% 7% 36%	2738
June	1st to 10th	Night	22% 8% 2 7% 5% 5% 4 5% 4 7% 32%	1520
	11th to 20th	Night	17% 7% 3 6% 5% 3 4 4 6% 8% 38%	1520
	21st to end	Night	23% 7% 3 5% 5% 4 4 3 6% 7% 32%	1520
July	1st to 10th	Night	13% 8% 3 7% 6% 5% 6% 5% 7% 9% 33%	2520
	11th to 20th	Night	13% 7% 3 8% 4 4 5% 4 7% 9% 36%	2520
	21st to end	Night	16% 6% 2 6% 4 4 5% 5% 6% 8% 38%	2739
August	1st to 10th	Night	21% 7% 3 8% 5% 4 4 4 6% 7% 32%	2777
	11th to 20th	Night	16% 9% 3 7% 5% 4 5% 4 7% 8% 33%	2782
	21st to end	Night	11% 5% 2 6% 4 4 4 3 6% 8% 46%	3311
September	1st to 10th	Night	12% 6% 2 5% 4 4 3 3 5% 6% 49%	1943
	11th to 20th	Night	15% 6% 2 4 3 3 3 3 4 7% 50%	2090
	21st to end	Night	15% 7% 2 5% 3 3 3 3 4 7% 48%	2090
October	1st to 10th	Night	18% 7% 2 6% 5% 3 5% 4 5% 6% 39%	2090
	11th to 20th	Night	17% 6% 2 6% 4 4 4 3 5% 6% 42%	2344
	21st to end	Night	25% 6% 2 5% 4 3 3 3 5% 5% 38%	2717
November	1st to 10th	Night	16% 6% 2 5% 4 4 4 4 5% 5% 45%	2537
	11th to 20th	Night	18% 5% 2 4 4 4 4 3 5% 5% 45%	2600
	21st to end	Night	17% 8% 3 5% 4 3 3 4 5% 6% 42%	2529
December	1st to 10th	Night	21% 10% 3 5% 4 4 4 3 5% 5% 36%	2789
	11th to 20th	Night	21% 7% 2 5% 4 3 3 3 5% 5% 41%	3404
	21st to end	Night	24% 10% 3 7% 4 4 4 2 4 5% 34%	4884

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	44% 4 11% 29% 12% 1	2518
	11th to 20th	Day	44% 4 13% 26% 12% 2	2520
	21st to end	Day	48% 3 12% 22% 13% 1	2772
February	1st to 10th	Day	47% 4 12% 20% 14% 3	1680
	11th to 20th	Day	45% 5% 11% 20% 14% 4	1857
	21st to end	Day	49% 3 9% 22% 13% 4	1570
March	1st to 10th	Day	58% 3 9% 13% 15% 3	3119
	11th to 20th	Day	42% 5% 12% 22% 15% 4	3411
	21st to end	Day	49% 5% 5% 16% 19% 7%	3910
April	1st to 10th	Day	49% 4 8% 18% 16% 4	2280
	11th to 20th	Day	43% 5% 10% 25% 14% 3	2347
	21st to end	Day	50% 4 9% 18% 16% 4	2470
May	1st to 10th	Day	54% 7% 13% 17% 9% 1	4120
	11th to 20th	Day	48% 7% 16% 17% 10% 2	4142
	21st to end	Day	41% 9% 15% 21% 13% 1	4837
June	1st to 10th	Day	50% 5% 13% 23% 9%	2660
	11th to 20th	Day	42% 5% 13% 22% 16% 3	2660
	21st to end	Day	51% 6% 11% 21% 10% 1	2660
July	1st to 10th	Day	44% 5% 12% 26% 13%	4370
	11th to 20th	Day	40% 5% 17% 27% 11%	4365
	21st to end	Day	45% 5% 14% 23% 12% 1	4661
August	1st to 10th	Day	45% 5% 17% 26% 8%	4105
	11th to 20th	Day	48% 4 16% 24% 8%	4084
	21st to end	Day	33% 5% 15% 27% 20% 1	4340
September	1st to 10th	Day	33% 6% 14% 29% 18% 1	2237
	11th to 20th	Day	32% 4 10% 29% 22% 2	2090
	21st to end	Day	38% 6% 9% 28% 17% 2	2090
October	1st to 10th	Day	46% 3 9% 24% 16% 1	3480
	11th to 20th	Day	35% 3 9% 31% 22% 1	3009
	21st to end	Day	36% 2 11% 27% 21% 3	3081
November	1st to 10th	Day	38% 4 13% 26% 17% 3	1761
	11th to 20th	Day	38% 5% 9% 23% 21% 4	1800
	21st to end	Day	45% 4 16% 21% 13% 1	1746
December	1st to 10th	Day	50% 4 10% 22% 13% 2	1378
	11th to 20th	Day	45% 5% 9% 21% 15% 5%	1774
	21st to end	Day	55% 4 10% 18% 9% 3	2772
January	1st to 10th	Night	43% 3 13% 28% 10% 3	4429
	11th to 20th	Night	46% 6% 12% 21% 12% 3	4440
	21st to end	Night	53% 3 9% 22% 11% 2	4884
February	1st to 10th	Night	49% 4 11% 19% 14% 3	2493
	11th to 20th	Night	46% 5% 8% 22% 17% 3	2220
	21st to end	Night	45% 4 9% 23% 15% 5%	1884
March	1st to 10th	Night	56% 3 9% 17% 12% 4	3734
	11th to 20th	Night	47% 6% 10% 22% 12% 3	3549
	21st to end	Night	52% 5% 6% 16% 16% 6%	3706
April	1st to 10th	Night	49% 4 8% 20% 15% 4	1900
	11th to 20th	Night	45% 4 8% 22% 18% 2	1780
	21st to end	Night	49% 5% 10% 17% 15% 4	1710
May	1st to 10th	Night	53% 6% 15% 17% 8% 1	2840
	11th to 20th	Night	53% 6% 14% 18% 7% 2	2784
	21st to end	Night	46% 7% 13% 19% 13% 1	2739
June	1st to 10th	Night	52% 6% 10% 21% 10% 1	1520
	11th to 20th	Night	43% 6% 15% 20% 15% 2	1520
	21st to end	Night	50% 6% 13% 22% 9% 1	1520
July	1st to 10th	Night	47% 5% 15% 19% 13% 1	2480
	11th to 20th	Night	44% 5% 12% 24% 14%	2472
	21st to end	Night	43% 5% 12% 26% 12% 1	2651
August	1st to 10th	Night	52% 5% 14% 20% 8% 1	2767
	11th to 20th	Night	47% 6% 14% 22% 11%	2809
	21st to end	Night	36% 4 14% 27% 18% 1	3311
September	1st to 10th	Night	36% 5% 10% 30% 17% 1	1943
	11th to 20th	Night	36% 4 9% 30% 19% 2	2090
	21st to end	Night	37% 5% 10% 30% 16% 2	2090
October	1st to 10th	Night	46% 4 12% 23% 15% 1	3480
	11th to 20th	Night	33% 3 8% 29% 25% 2	3906
	21st to end	Night	39% 2 10% 27% 19% 3	4467
November	1st to 10th	Night	40% 4 10% 28% 16% 2	2537
	11th to 20th	Night	40% 4 10% 24% 19% 3	2600
	21st to end	Night	43% 4 14% 22% 15% 2	2529
December	1st to 10th	Night	51% 4 10% 22% 12% 1	2789
	11th to 20th	Night	44% 4 11% 21% 18% 1	3404
	21st to end	Night	54% 3 11% 19% 11% 1	4884

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% 19% 24% 22% 7%	180
	11th to 20th	Day	28% 15% 29% 22% 5% 1	180
	21st to end	Day	21% 14% 38% 18% 9%	198
February	1st to 10th	Day	29% 12% 38% 18% 3	338
	11th to 20th	Day	22% 20% 40% 15% 2	456
	21st to end	Day	25% 14% 37% 19% 5%	382
March	1st to 10th	Day	26% 12% 40% 18% 4	460
	11th to 20th	Day	22% 20% 38% 17% 2 1	460
	21st to end	Day	26% 19% 32% 15% 6% 2	506
April	1st to 10th	Day	29% 16% 32% 17% 5% 2	460
	11th to 20th	Day	24% 16% 34% 18% 7% 2	452
	21st to end	Day	30% 12% 33% 18% 4 3	460
May	1st to 10th	Day	28% 15% 31% 19% 5% 2	463
	11th to 20th	Day	20% 12% 39% 20% 7% 2	487
	21st to end	Day	21% 10% 34% 26% 8% 2	529
June	1st to 10th	Day	22% 9% 35% 25% 7% 3	490
	11th to 20th	Day	14% 12% 38% 23% 11% 2	490
	21st to end	Day	24% 8% 33% 26% 8% 2	490
July	1st to 10th	Day	19% 5% 32% 27% 13% 4	485
	11th to 20th	Day	14% 6% 33% 30% 13% 4	484
	21st to end	Day	15% 4 32% 31% 14% 4	532
August	1st to 10th	Day	14% 6% 26% 34% 16% 3	486
	11th to 20th	Day	19% 4 26% 30% 14% 7%	479
	21st to end	Day	13% 6% 29% 29% 15% 8%	539
September	1st to 10th	Day	15% 7% 29% 29% 15% 5%	490
	11th to 20th	Day	16% 9% 31% 24% 13% 8%	490
	21st to end	Day	18% 9% 30% 24% 12% 6%	490
October	1st to 10th	Day	23% 10% 23% 26% 13% 4	490
	11th to 20th	Day	21% 12% 30% 23% 11% 4	396
	21st to end	Day	29% 12% 28% 22% 8%	429
November	1st to 10th	Day	23% 14% 28% 23% 10% 2	395
	11th to 20th	Day	25% 17% 31% 20% 6% 1	400
	21st to end	Day	29% 12% 29% 20% 7% 2	382
December	1st to 10th	Day	25% 14% 35% 17% 9% 1	209
	11th to 20th	Day	26% 16% 35% 18% 4	180
	21st to end	Day	29% 19% 28% 17% 7% 1	198
January	1st to 10th	Night	22% 18% 35% 20% 4	760
	11th to 20th	Night	24% 19% 34% 19% 4	760
	21st to end	Night	20% 19% 38% 20% 3	836
February	1st to 10th	Night	23% 16% 37% 21% 3	760
	11th to 20th	Night	22% 18% 38% 20% 2	743
	21st to end	Night	22% 15% 34% 24% 5%	628
March	1st to 10th	Night	24% 17% 36% 21% 2	760
	11th to 20th	Night	23% 13% 34% 22% 8%	760
	21st to end	Night	26% 13% 32% 24% 5% 1	836
April	1st to 10th	Night	27% 11% 31% 25% 5%	760
	11th to 20th	Night	22% 10% 35% 24% 9%	656
	21st to end	Night	26% 10% 28% 29% 6% 1	570
May	1st to 10th	Night	26% 7% 29% 28% 9% 1	570
	11th to 20th	Night	23% 7% 32% 29% 9% 1	545
	21st to end	Night	26% 6% 21% 33% 12% 1	411
June	1st to 10th	Night	25% 7% 20% 33% 13% 2	380
	11th to 20th	Night	20% 4 22% 35% 18% 1	380
	21st to end	Night	25% 5% 18% 38% 13%	380
July	1st to 10th	Night	19% 3 14% 45% 18% 2	370
	11th to 20th	Night	20% 3 16% 38% 21% 2	368
	21st to end	Night	17% 3 14% 42% 23% 2	416
August	1st to 10th	Night	16% 3 17% 43% 19% 2	532
	11th to 20th	Night	17% 4 17% 39% 21% 3	562
	21st to end	Night	17% 4 18% 38% 20% 3	736
September	1st to 10th	Night	15% 3 26% 35% 19% 2	760
	11th to 20th	Night	19% 6% 25% 27% 19% 4	760
	21st to end	Night	19% 6% 24% 32% 17% 3	760
October	1st to 10th	Night	22% 8% 21% 30% 17% 2	760
	11th to 20th	Night	20% 10% 30% 27% 12% 1	760
	21st to end	Night	29% 9% 29% 26% 7%	836
November	1st to 10th	Night	21% 10% 34% 27% 7% 2	780
	11th to 20th	Night	24% 14% 32% 22% 7% 1	800
	21st to end	Night	23% 17% 32% 21% 6%	779
December	1st to 10th	Night	26% 15% 36% 18% 5% 1	838
	11th to 20th	Night	23% 20% 32% 20% 4	812
	21st to end	Night	27% 15% 35% 20% 3	836

Page generated at 2024-11-22 08:02:28. Version ac07

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