Cranberry Corner
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Cranberry Corner clear sky chart from 2005-11-06 to 2024-02-10.

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% 11% 5% 9% 6% 4 5% 5% 5% 6% 31%	78128
	Night	14% 12% 5% 9% 7% 4 5% 5% 5% 6% 30%	80884
Transparency	Day	53% 6% 12% 19% 9% 1	77834
	Night	54% 6% 12% 19% 8% 1	80712
Seeing	Day	19% 17% 33% 20% 8% 2	14967
	Night	19% 14% 34% 24% 9% 1	25044

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	12% 16% 9% 20% 7% 4 4 4 4 5% 15%	2527
	11th to 20th	Day	8% 16% 7% 15% 11% 6% 9% 7% 5% 4 11%	2530
	21st to end	Day	10% 15% 13% 19% 8% 3 4 4 4 5% 15%	2783
February	1st to 10th	Day	9% 13% 4 10% 7% 5% 8% 6% 5% 7% 25%	1697
	11th to 20th	Day	9% 11% 6% 13% 9% 4 5% 6% 5% 5% 27%	1610
	21st to end	Day	13% 12% 7% 13% 10% 6% 5% 4 3 6% 22%	1480
March	1st to 10th	Day	12% 11% 5% 10% 8% 5% 5% 4 4 7% 29%	1798
	11th to 20th	Day	13% 9% 6% 9% 7% 3 4 4 4 6% 36%	1921
	21st to end	Day	16% 12% 6% 8% 7% 4 4 5% 4 6% 28%	2334
April	1st to 10th	Day	15% 13% 6% 9% 7% 3 5% 5% 4 6% 27%	2160
	11th to 20th	Day	19% 13% 6% 7% 6% 3 4 3 4 5% 30%	2134
	21st to end	Day	19% 12% 4 7% 6% 3 5% 5% 5% 5% 32%	2295
May	1st to 10th	Day	17% 11% 4 7% 6% 3 5% 5% 4 6% 34%	2520
	11th to 20th	Day	17% 10% 3 6% 5% 3 4 5% 6% 6% 34%	2479
	21st to end	Day	15% 7% 3 6% 6% 4 5% 5% 5% 7% 36%	2725
June	1st to 10th	Day	15% 5% 2 6% 5% 3 5% 6% 5% 8% 40%	2520
	11th to 20th	Day	15% 6% 3 6% 5% 4 6% 5% 5% 7% 38%	2520
	21st to end	Day	14% 6% 3 6% 5% 4 5% 5% 6% 8% 37%	2520
July	1st to 10th	Day	8% 3 2 5% 4 3 5% 6% 6% 10% 47%	2520
	11th to 20th	Day	13% 5% 2 5% 5% 3 4 4 5% 8% 45%	2520
	21st to end	Day	9% 4 2 5% 5% 4 5% 5% 6% 9% 46%	2743
August	1st to 10th	Day	12% 6% 3 5% 5% 3 5% 6% 6% 8% 40%	2507
	11th to 20th	Day	15% 7% 3 4 5% 3 5% 4 5% 7% 42%	2310
	21st to end	Day	15% 6% 2 6% 4 3 5% 5% 4 8% 42%	2376
September	1st to 10th	Day	16% 7% 3 5% 4 3 4 5% 5% 8% 41%	2160
	11th to 20th	Day	15% 7% 3 6% 5% 3 4 4 5% 8% 39%	2124
	21st to end	Day	21% 9% 3 6% 5% 3 5% 4 5% 7% 32%	1973
October	1st to 10th	Day	20% 12% 2 6% 4 3 4 4 6% 6% 33%	1800
	11th to 20th	Day	21% 17% 5% 6% 5% 3 5% 4 5% 5% 23%	1797
	21st to end	Day	22% 17% 5% 8% 5% 2 4 4 4 5% 24%	1782
November	1st to 10th	Day	15% 15% 5% 7% 6% 3 4 5% 5% 6% 29%	1672
	11th to 20th	Day	16% 16% 7% 12% 8% 3 5% 4 4 5% 19%	1554
	21st to end	Day	14% 14% 9% 15% 9% 4 4 4 5% 5% 17%	1520
December	1st to 10th	Day	12% 15% 8% 16% 10% 5% 5% 5% 4 4 14%	1520
	11th to 20th	Day	13% 15% 7% 12% 13% 5% 7% 5% 5% 5% 14%	1914
	21st to end	Day	20% 23% 8% 14% 7% 4 4 3 3 3 12%	2783
January	1st to 10th	Night	12% 15% 7% 19% 10% 4 5% 3 4 4 18%	4428
	11th to 20th	Night	9% 15% 7% 14% 11% 8% 7% 6% 6% 6% 12%	4440
	21st to end	Night	11% 17% 10% 18% 7% 4 4 4 4 5% 17%	4884
February	1st to 10th	Night	8% 11% 7% 11% 9% 5% 6% 5% 6% 6% 25%	2464
	11th to 20th	Night	9% 9% 5% 9% 10% 6% 7% 5% 6% 7% 26%	2237
	21st to end	Night	12% 17% 6% 9% 8% 4 5% 5% 6% 5% 24%	1776
March	1st to 10th	Night	13% 9% 4 8% 7% 3 4 5% 5% 5% 35%	2149
	11th to 20th	Night	12% 12% 4 6% 6% 3 4 4 5% 5% 39%	2053
	21st to end	Night	15% 11% 5% 7% 7% 3 4 5% 5% 6% 34%	2021
April	1st to 10th	Night	19% 11% 5% 8% 5% 3 4 5% 6% 6% 29%	1800
	11th to 20th	Night	22% 10% 4 7% 4 2 3 4 5% 6% 33%	1775
	21st to end	Night	18% 9% 4 6% 5% 3 4 5% 5% 5% 34%	1662
May	1st to 10th	Night	18% 10% 4 7% 6% 3 5% 5% 5% 6% 31%	1440
	11th to 20th	Night	17% 8% 3 6% 6% 3 5% 3 5% 5% 38%	1416
	21st to end	Night	13% 7% 3 6% 5% 3 5% 4 6% 9% 39%	1551
June	1st to 10th	Night	12% 6% 2 5% 5% 3 4 4 5% 7% 45%	1440
	11th to 20th	Night	12% 7% 3 5% 5% 4 5% 5% 6% 7% 41%	1440
	21st to end	Night	13% 6% 2 5% 5% 3 4 4 6% 9% 43%	1440
July	1st to 10th	Night	9% 4 2 3 4 2 4 5% 6% 9% 52%	1440
	11th to 20th	Night	11% 5% 3 5% 4 2 5% 5% 5% 8% 47%	1440
	21st to end	Night	9% 4 1 4 4 2 4 4 6% 8% 54%	1575
August	1st to 10th	Night	10% 5% 2 4 6% 2 5% 5% 6% 7% 49%	1432
	11th to 20th	Night	13% 6% 2 5% 4 2 4 4 5% 6% 50%	1588
	21st to end	Night	14% 7% 2 4 5% 2 3 3 4 7% 49%	1980
September	1st to 10th	Night	14% 4 3 4 4 3 4 5% 5% 7% 48%	1800
	11th to 20th	Night	13% 5% 2 4 4 3 5% 5% 5% 8% 46%	1817
	21st to end	Night	17% 7% 4 5% 6% 3 4 5% 5% 7% 37%	1984
October	1st to 10th	Night	18% 8% 2 4 5% 3 4 4 6% 7% 40%	2160
	11th to 20th	Night	19% 13% 5% 5% 5% 4 5% 4 5% 6% 30%	2162
	21st to end	Night	20% 15% 4 7% 6% 4 5% 5% 5% 6% 25%	2574
November	1st to 10th	Night	15% 13% 5% 6% 5% 3 4 4 5% 7% 32%	2406
	11th to 20th	Night	15% 15% 9% 11% 7% 4 4 4 3 5% 22%	2623
	21st to end	Night	14% 15% 6% 12% 8% 4 5% 4 5% 7% 21%	2660
December	1st to 10th	Night	12% 15% 8% 13% 10% 4 6% 5% 5% 5% 18%	2660
	11th to 20th	Night	11% 15% 8% 14% 10% 4 6% 6% 5% 5% 18%	3283
	21st to end	Night	23% 21% 6% 11% 6% 3 3 4 3 4 14%	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	72% 4 6% 14% 3	2528
	11th to 20th	Day	73% 6% 10% 8% 4	2530
	21st to end	Day	71% 5% 10% 10% 4	2783
February	1st to 10th	Day	57% 5% 12% 16% 10%	1697
	11th to 20th	Day	57% 6% 11% 20% 6%	1619
	21st to end	Day	64% 5% 8% 13% 9% 1	1480
March	1st to 10th	Day	56% 5% 15% 14% 9% 1	1800
	11th to 20th	Day	51% 5% 14% 19% 10% 1	1921
	21st to end	Day	58% 6% 11% 17% 7% 1	2334
April	1st to 10th	Day	58% 5% 11% 16% 9% 1	2160
	11th to 20th	Day	57% 5% 10% 18% 9% 1	2134
	21st to end	Day	54% 7% 10% 17% 11% 1	2295
May	1st to 10th	Day	50% 7% 11% 21% 9% 1	2520
	11th to 20th	Day	49% 7% 12% 20% 11% 1	2483
	21st to end	Day	47% 6% 12% 21% 12% 2	2725
June	1st to 10th	Day	40% 8% 14% 27% 11% 1	2520
	11th to 20th	Day	44% 8% 13% 21% 14% 1	2520
	21st to end	Day	42% 9% 17% 23% 8% 1	2520
July	1st to 10th	Day	29% 9% 18% 31% 13% 1	2451
	11th to 20th	Day	37% 7% 13% 26% 14% 3	2445
	21st to end	Day	34% 8% 16% 25% 16% 1	2591
August	1st to 10th	Day	39% 9% 16% 25% 9% 2	2492
	11th to 20th	Day	41% 8% 16% 23% 12%	2310
	21st to end	Day	41% 7% 14% 23% 14% 1	2376
September	1st to 10th	Day	42% 6% 14% 27% 11%	2160
	11th to 20th	Day	43% 7% 18% 24% 8%	2124
	21st to end	Day	51% 7% 12% 23% 6%	1973
October	1st to 10th	Day	50% 6% 13% 23% 7%	1800
	11th to 20th	Day	62% 5% 11% 15% 7%	1797
	21st to end	Day	62% 5% 12% 16% 6%	1782
November	1st to 10th	Day	55% 6% 12% 19% 7% 1	1672
	11th to 20th	Day	69% 5% 10% 11% 6%	1554
	21st to end	Day	68% 6% 12% 10% 3 1	1520
December	1st to 10th	Day	71% 5% 10% 11% 3	1520
	11th to 20th	Day	72% 6% 10% 9% 4	1915
	21st to end	Day	79% 4 5% 9% 3	2783
January	1st to 10th	Night	69% 5% 8% 14% 2	4428
	11th to 20th	Night	69% 7% 12% 10% 3	4440
	21st to end	Night	69% 5% 8% 14% 3	4884
February	1st to 10th	Night	58% 4 10% 17% 10% 1	2464
	11th to 20th	Night	55% 7% 11% 19% 7% 1	2238
	21st to end	Night	60% 6% 10% 15% 8% 1	1776
March	1st to 10th	Night	49% 6% 13% 19% 12% 1	2160
	11th to 20th	Night	47% 6% 13% 22% 11% 1	2054
	21st to end	Night	51% 7% 11% 18% 12% 1	2021
April	1st to 10th	Night	54% 6% 10% 18% 12% 1	1800
	11th to 20th	Night	53% 4 9% 21% 11% 2	1775
	21st to end	Night	50% 5% 12% 19% 13% 1	1662
May	1st to 10th	Night	52% 6% 14% 18% 9% 1	1440
	11th to 20th	Night	47% 7% 10% 22% 11% 3	1417
	21st to end	Night	42% 8% 17% 20% 12% 2	1552
June	1st to 10th	Night	36% 8% 17% 27% 12%	1440
	11th to 20th	Night	42% 7% 13% 21% 15% 1	1440
	21st to end	Night	36% 9% 16% 28% 10% 1	1440
July	1st to 10th	Night	26% 8% 15% 34% 17% 1	1400
	11th to 20th	Night	34% 8% 15% 27% 14% 2	1392
	21st to end	Night	27% 8% 17% 30% 16% 3	1487
August	1st to 10th	Night	33% 8% 14% 30% 12% 2	1423
	11th to 20th	Night	35% 10% 13% 26% 14% 2	1588
	21st to end	Night	36% 6% 15% 26% 15% 3	1980
September	1st to 10th	Night	34% 8% 14% 30% 13% 1	1800
	11th to 20th	Night	36% 7% 17% 33% 8%	1817
	21st to end	Night	46% 6% 15% 25% 8%	1984
October	1st to 10th	Night	44% 8% 12% 25% 10% 1	2160
	11th to 20th	Night	54% 6% 14% 19% 7% 1	2162
	21st to end	Night	59% 7% 12% 16% 6%	2574
November	1st to 10th	Night	51% 5% 14% 20% 9%	2406
	11th to 20th	Night	64% 5% 12% 11% 7% 1	2623
	21st to end	Night	64% 6% 12% 13% 3 1	2660
December	1st to 10th	Night	67% 6% 12% 12% 3	2660
	11th to 20th	Night	67% 7% 11% 12% 4	3281
	21st to end	Night	74% 4 6% 11% 4	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	18% 18% 35% 21% 6% 2	270
	11th to 20th	Day	26% 14% 36% 22% 2	270
	21st to end	Day	19% 16% 42% 21% 3	297
February	1st to 10th	Day	18% 23% 41% 12% 4 1	267
	11th to 20th	Day	14% 32% 38% 12% 3 1	240
	21st to end	Day	21% 28% 43% 7%	198
March	1st to 10th	Day	18% 27% 34% 19% 3	240
	11th to 20th	Day	20% 21% 37% 17% 5%	240
	21st to end	Day	22% 19% 35% 16% 6% 2	420
April	1st to 10th	Day	23% 19% 37% 16% 5%	420
	11th to 20th	Day	31% 16% 27% 19% 7% 1	412
	21st to end	Day	23% 20% 30% 19% 6% 2	446
May	1st to 10th	Day	21% 22% 34% 16% 5% 2	603
	11th to 20th	Day	21% 16% 34% 20% 6% 3	625
	21st to end	Day	22% 13% 34% 20% 10% 2	679
June	1st to 10th	Day	14% 16% 34% 24% 9% 3	630
	11th to 20th	Day	18% 14% 38% 19% 9% 2	630
	21st to end	Day	13% 17% 34% 21% 11% 4	630
July	1st to 10th	Day	8% 10% 34% 29% 14% 6%	621
	11th to 20th	Day	14% 11% 34% 24% 12% 5%	618
	21st to end	Day	9% 10% 38% 24% 13% 7%	684
August	1st to 10th	Day	14% 9% 30% 29% 15% 4	626
	11th to 20th	Day	16% 9% 23% 32% 16% 4	579
	21st to end	Day	20% 10% 27% 24% 15% 4	495
September	1st to 10th	Day	20% 14% 23% 27% 12% 4	450
	11th to 20th	Day	17% 10% 34% 27% 11% 2	450
	21st to end	Day	26% 16% 26% 22% 7% 3	443
October	1st to 10th	Day	23% 20% 27% 19% 9% 1	270
	11th to 20th	Day	24% 31% 29% 13% 4	270
	21st to end	Day	34% 23% 34% 8% 1	297
November	1st to 10th	Day	24% 18% 37% 15% 5%	270
	11th to 20th	Day	25% 25% 38% 9% 2 1	270
	21st to end	Day	21% 24% 41% 10% 4	270
December	1st to 10th	Day	20% 19% 42% 14% 5%	270
	11th to 20th	Day	25% 24% 34% 15% 2	270
	21st to end	Day	23% 28% 36% 11% 1 1	297
January	1st to 10th	Night	16% 18% 42% 19% 5% 1	950
	11th to 20th	Night	18% 17% 42% 17% 6% 1	950
	21st to end	Night	19% 14% 40% 21% 5%	1045
February	1st to 10th	Night	16% 16% 40% 21% 6%	948
	11th to 20th	Night	16% 20% 39% 19% 5% 1	843
	21st to end	Night	20% 16% 41% 20% 3	592
March	1st to 10th	Night	17% 16% 35% 25% 7% 1	720
	11th to 20th	Night	19% 15% 40% 20% 7%	614
	21st to end	Night	20% 15% 29% 26% 10% 1	594
April	1st to 10th	Night	22% 13% 37% 21% 7%	540
	11th to 20th	Night	27% 11% 28% 26% 8%	533
	21st to end	Night	24% 12% 31% 24% 9% 1	540
May	1st to 10th	Night	21% 14% 32% 26% 6% 1	540
	11th to 20th	Night	20% 9% 34% 28% 8% 2	531
	21st to end	Night	15% 12% 29% 32% 11% 1	584
June	1st to 10th	Night	15% 8% 32% 33% 11% 1	540
	11th to 20th	Night	17% 9% 33% 32% 9%	540
	21st to end	Night	15% 7% 29% 33% 14% 1	540
July	1st to 10th	Night	8% 5% 28% 36% 22% 1	525
	11th to 20th	Night	13% 7% 33% 30% 16% 1	522
	21st to end	Night	10% 3 28% 39% 17% 3	591
August	1st to 10th	Night	12% 4 26% 37% 20% 1	537
	11th to 20th	Night	16% 6% 20% 34% 22% 2	534
	21st to end	Night	15% 6% 29% 28% 21% 1	594
September	1st to 10th	Night	15% 7% 26% 33% 16% 3	540
	11th to 20th	Night	14% 8% 33% 29% 14% 1	557
	21st to end	Night	22% 11% 30% 26% 10% 1	720
October	1st to 10th	Night	23% 12% 28% 24% 12% 1	720
	11th to 20th	Night	26% 17% 31% 21% 6%	720
	21st to end	Night	28% 13% 31% 21% 7%	792
November	1st to 10th	Night	24% 14% 37% 19% 5% 1	740
	11th to 20th	Night	23% 22% 35% 16% 4 1	913
	21st to end	Night	22% 23% 35% 16% 3	950
December	1st to 10th	Night	19% 22% 37% 17% 5% 1	950
	11th to 20th	Night	19% 21% 36% 19% 5% 1	950
	21st to end	Night	27% 19% 36% 15% 4	1045

Page generated at 2024-02-07 05:11:59. Version ac07

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