Pine Islands
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Pine Islands clear sky chart from 2005-11-06 to 2024-11-04.

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	16% 10% 3 8% 5% 4 4 3 5% 7% 34%	101750
	Night	17% 13% 4 9% 5% 4 4 3 5% 6% 29%	97275
Transparency	Day	26% 48% 7% 12% 6%	105319
	Night	29% 48% 7% 10% 5%	101784
Seeing	Day	21% 12% 28% 24% 12% 3	15033
	Night	23% 12% 27% 25% 11% 1	24061

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	17% 21% 14% 11% 4 4 5% 3 3 4 14%	2208
	11th to 20th	Day	12% 18% 9% 21% 9% 5% 5% 4 4 4 10%	2649
	21st to end	Day	17% 22% 7% 12% 6% 4 4 3 4 4 15%	3124
February	1st to 10th	Day	13% 19% 6% 16% 7% 5% 4 3 3 4 19%	1710
	11th to 20th	Day	12% 16% 5% 11% 7% 5% 4 3 5% 6% 27%	1663
	21st to end	Day	16% 17% 7% 9% 5% 5% 4 3 4 5% 25%	1462
March	1st to 10th	Day	19% 12% 4 8% 4 5% 4 3 4 5% 32%	3398
	11th to 20th	Day	11% 14% 5% 9% 6% 6% 5% 3 5% 6% 29%	3480
	21st to end	Day	13% 9% 3 6% 5% 4 5% 4 6% 6% 37%	3815
April	1st to 10th	Day	20% 11% 3 7% 5% 5% 4 3 5% 5% 33%	2228
	11th to 20th	Day	22% 8% 3 5% 3 4 4 3 5% 6% 37%	2390
	21st to end	Day	21% 8% 3 6% 5% 4 4 3 5% 6% 36%	2470
May	1st to 10th	Day	18% 7% 2 7% 4 4 4 3 6% 7% 38%	4108
	11th to 20th	Day	12% 8% 2 6% 4 5% 4 4 6% 8% 41%	4398
	21st to end	Day	16% 6% 2 5% 4 4 4 4 6% 7% 43%	4837
June	1st to 10th	Day	16% 7% 2 5% 4 4 5% 4 6% 7% 39%	2717
	11th to 20th	Day	12% 5% 2 5% 5% 4 5% 4 6% 9% 43%	2850
	21st to end	Day	16% 8% 3 5% 3 4 4 4 6% 8% 39%	2850
July	1st to 10th	Day	14% 5% 2 7% 5% 5% 5% 4 6% 8% 39%	4760
	11th to 20th	Day	12% 6% 2 4 3 3 4 3 5% 8% 50%	4610
	21st to end	Day	10% 5% 2 6% 3 3 3 3 5% 8% 52%	4547
August	1st to 10th	Day	12% 6% 2 6% 4 4 4 4 6% 9% 42%	4104
	11th to 20th	Day	15% 6% 2 5% 3 3 4 3 6% 9% 43%	4044
	21st to end	Day	9% 4 2 6% 4 4 4 4 6% 9% 48%	4436
September	1st to 10th	Day	14% 6% 2 6% 5% 4 4 3 6% 7% 44%	2280
	11th to 20th	Day	13% 6% 2 6% 4 4 3 4 5% 7% 46%	2139
	21st to end	Day	18% 8% 3 7% 5% 5% 4 3 5% 6% 37%	2071
October	1st to 10th	Day	22% 8% 2 6% 4 4 4 3 4 6% 36%	1900
	11th to 20th	Day	26% 10% 4 9% 5% 4 4 4 3 7% 24%	1900
	21st to end	Day	31% 12% 4 9% 4 4 4 3 4 5% 19%	2066
November	1st to 10th	Day	20% 17% 4 8% 6% 4 3 3 5% 7% 24%	1581
	11th to 20th	Day	21% 16% 5% 10% 6% 5% 5% 4 4 6% 16%	1520
	21st to end	Day	25% 21% 4 9% 8% 6% 4 4 4 4 10%	1520
December	1st to 10th	Day	18% 30% 6% 10% 7% 5% 5% 3 4 3 10%	1520
	11th to 20th	Day	20% 25% 7% 13% 6% 4 4 3 3 4 13%	1906
	21st to end	Day	27% 18% 5% 12% 6% 6% 5% 3 3 4 11%	2489
January	1st to 10th	Night	17% 25% 12% 15% 6% 5% 4 3 3 3 10%	4748
	11th to 20th	Night	15% 18% 7% 23% 7% 6% 4 3 3 4 11%	4305
	21st to end	Night	17% 19% 8% 13% 6% 5% 4 4 4 5% 15%	4532
February	1st to 10th	Night	14% 21% 6% 13% 8% 6% 4 3 5% 5% 17%	2470
	11th to 20th	Night	14% 16% 6% 13% 7% 5% 4 3 4 5% 23%	2403
	21st to end	Night	17% 14% 5% 11% 5% 5% 5% 3 4 5% 25%	1989
March	1st to 10th	Night	16% 13% 4 8% 5% 3 5% 3 5% 6% 32%	3441
	11th to 20th	Night	12% 16% 5% 9% 6% 4 4 4 4 6% 32%	3479
	21st to end	Night	14% 10% 4 8% 6% 6% 5% 4 5% 5% 31%	3817
April	1st to 10th	Night	22% 12% 3 7% 6% 4 4 3 5% 4 31%	1951
	11th to 20th	Night	19% 9% 3 7% 4 4 4 3 5% 6% 35%	1754
	21st to end	Night	20% 8% 4 9% 5% 5% 4 3 4 6% 32%	1710
May	1st to 10th	Night	16% 6% 2 7% 5% 5% 5% 4 6% 7% 38%	2833
	11th to 20th	Night	15% 8% 3 6% 5% 4 4 3 5% 7% 40%	2495
	21st to end	Night	11% 6% 2 6% 5% 4 4 4 5% 8% 44%	2738
June	1st to 10th	Night	15% 8% 3 5% 6% 4 5% 3 6% 6% 38%	1458
	11th to 20th	Night	12% 5% 2 5% 4 5% 4 4 6% 9% 44%	1330
	21st to end	Night	15% 7% 3 5% 4 5% 4 3 7% 6% 41%	1330
July	1st to 10th	Night	10% 7% 3 7% 5% 3 4 3 5% 8% 45%	2210
	11th to 20th	Night	14% 5% 2 5% 4 3 4 2 4 7% 50%	2351
	21st to end	Night	9% 5% 2 5% 4 4 4 4 5% 7% 50%	2990
August	1st to 10th	Night	11% 6% 2 6% 4 4 4 4 6% 7% 45%	2825
	11th to 20th	Night	15% 6% 3 6% 4 4 4 3 5% 7% 44%	2785
	21st to end	Night	15% 5% 2 5% 4 3 4 3 5% 7% 47%	3188
September	1st to 10th	Night	12% 5% 2 6% 4 4 4 4 5% 7% 46%	1900
	11th to 20th	Night	13% 5% 2 6% 5% 3 5% 3 6% 7% 45%	2038
	21st to end	Night	20% 6% 2 6% 5% 4 4 3 6% 7% 37%	2109
October	1st to 10th	Night	21% 9% 3 8% 4 4 4 3 4 6% 34%	2280
	11th to 20th	Night	28% 11% 3 8% 5% 4 4 3 5% 6% 23%	2280
	21st to end	Night	29% 14% 4 9% 5% 3 4 3 5% 5% 19%	2527
November	1st to 10th	Night	22% 16% 3 8% 5% 3 4 2 5% 5% 26%	2569
	11th to 20th	Night	19% 21% 5% 10% 5% 5% 5% 3 5% 4 19%	2660
	21st to end	Night	26% 22% 6% 10% 6% 4 4 3 4 4 12%	2660
December	1st to 10th	Night	21% 30% 6% 12% 6% 4 3 2 3 3 8%	2660
	11th to 20th	Night	19% 24% 7% 12% 6% 4 4 3 3 5% 13%	3288
	21st to end	Night	25% 21% 7% 15% 7% 4 3 3 3 4 8%	5172

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	46% 40% 7% 5% 1	2209
	11th to 20th	Day	51% 40% 4 3 1	2649
	21st to end	Day	45% 43% 5% 4 3	3124
February	1st to 10th	Day	27% 66% 2 4 1	1710
	11th to 20th	Day	20% 65% 4 7% 4	1672
	21st to end	Day	23% 65% 3 7% 2	1462
March	1st to 10th	Day	35% 43% 9% 6% 7%	3401
	11th to 20th	Day	34% 44% 9% 9% 3 1	3480
	21st to end	Day	24% 45% 11% 13% 6% 1	3815
April	1st to 10th	Day	21% 65% 3 7% 4	2228
	11th to 20th	Day	18% 66% 3 9% 4 1	2390
	21st to end	Day	18% 66% 3 7% 5% 1	2470
May	1st to 10th	Day	27% 45% 7% 13% 8%	4120
	11th to 20th	Day	22% 45% 13% 15% 5%	4402
	21st to end	Day	24% 43% 9% 11% 11% 2	4837
June	1st to 10th	Day	15% 66% 3 10% 6%	2717
	11th to 20th	Day	15% 66% 4 8% 6% 1	2850
	21st to end	Day	16% 64% 4 9% 7%	2850
July	1st to 10th	Day	30% 37% 11% 14% 8%	4686
	11th to 20th	Day	22% 38% 11% 24% 6%	4529
	21st to end	Day	19% 36% 7% 23% 14%	4402
August	1st to 10th	Day	24% 40% 11% 18% 7%	4091
	11th to 20th	Day	28% 40% 11% 16% 5%	4083
	21st to end	Day	19% 39% 8% 27% 7%	4436
September	1st to 10th	Day	16% 62% 6% 11% 5%	2280
	11th to 20th	Day	13% 61% 4 15% 7%	2139
	21st to end	Day	17% 62% 5% 11% 5%	2071
October	1st to 10th	Day	26% 39% 10% 18% 7%	3160
	11th to 20th	Day	24% 40% 11% 21% 4	3140
	21st to end	Day	37% 38% 9% 13% 3	3380
November	1st to 10th	Day	29% 58% 6% 4 3	1581
	11th to 20th	Day	27% 61% 6% 5% 1	1520
	21st to end	Day	29% 61% 5% 3 1 1	1520
December	1st to 10th	Day	29% 61% 4 5% 1	1520
	11th to 20th	Day	38% 50% 7% 5% 1	1906
	21st to end	Day	49% 40% 6% 4 1	2489
January	1st to 10th	Night	53% 39% 4 3 2	4748
	11th to 20th	Night	50% 40% 5% 3 2	4305
	21st to end	Night	44% 43% 7% 3 2	4532
February	1st to 10th	Night	24% 66% 3 5% 2	2470
	11th to 20th	Night	20% 64% 3 9% 4	2405
	21st to end	Night	23% 66% 4 4 4	1989
March	1st to 10th	Night	31% 44% 7% 10% 7%	3451
	11th to 20th	Night	32% 44% 9% 10% 4 1	3480
	21st to end	Night	28% 46% 9% 11% 5% 1	3817
April	1st to 10th	Night	23% 65% 2 5% 4	1951
	11th to 20th	Night	17% 66% 2 7% 7% 1	1754
	21st to end	Night	20% 65% 5% 4 5% 1	1710
May	1st to 10th	Night	25% 45% 8% 16% 5% 1	2840
	11th to 20th	Night	25% 44% 9% 13% 8%	2496
	21st to end	Night	22% 44% 8% 16% 10% 1	2739
June	1st to 10th	Night	13% 65% 3 10% 8% 1	1458
	11th to 20th	Night	12% 64% 4 10% 9%	1330
	21st to end	Night	14% 64% 4 11% 7% 1	1330
July	1st to 10th	Night	28% 37% 9% 13% 11% 2	2175
	11th to 20th	Night	22% 36% 8% 27% 7%	2309
	21st to end	Night	21% 37% 6% 20% 16% 1	2895
August	1st to 10th	Night	24% 37% 11% 15% 12% 1	2814
	11th to 20th	Night	29% 39% 11% 15% 6%	2812
	21st to end	Night	21% 38% 7% 26% 9%	3188
September	1st to 10th	Night	11% 63% 7% 13% 6%	1900
	11th to 20th	Night	13% 61% 5% 13% 9%	2038
	21st to end	Night	17% 61% 5% 11% 6%	2109
October	1st to 10th	Night	22% 39% 6% 20% 12%	3800
	11th to 20th	Night	26% 39% 12% 19% 5%	3779
	21st to end	Night	31% 40% 14% 13% 3	4151
November	1st to 10th	Night	28% 59% 5% 5% 2	2569
	11th to 20th	Night	26% 60% 6% 6% 2	2660
	21st to end	Night	30% 61% 4 3 2	2660
December	1st to 10th	Night	32% 60% 3 3 1	2660
	11th to 20th	Night	37% 52% 5% 4 2	3288
	21st to end	Night	52% 38% 4 5% 1	5172

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	19% 25% 34% 13% 8% 1	180
	11th to 20th	Day	23% 22% 32% 16% 6% 1	234
	21st to end	Day	30% 12% 30% 21% 6%	297
February	1st to 10th	Day	30% 20% 33% 13% 3 1	270
	11th to 20th	Day	20% 23% 40% 15% 1	270
	21st to end	Day	34% 22% 33% 11%	225
March	1st to 10th	Day	22% 17% 36% 21% 4	437
	11th to 20th	Day	22% 17% 34% 22% 5% 1	460
	21st to end	Day	26% 15% 30% 22% 6% 1	506
April	1st to 10th	Day	23% 17% 30% 22% 8%	460
	11th to 20th	Day	31% 15% 25% 17% 9% 3	452
	21st to end	Day	27% 16% 31% 18% 7% 1	460
May	1st to 10th	Day	20% 9% 35% 24% 9% 3	463
	11th to 20th	Day	19% 8% 29% 28% 14% 3	487
	21st to end	Day	15% 9% 29% 29% 14% 4	529
June	1st to 10th	Day	19% 9% 28% 30% 13% 1	547
	11th to 20th	Day	15% 8% 29% 33% 12% 4	680
	21st to end	Day	20% 6% 27% 31% 14% 2	680
July	1st to 10th	Day	11% 7% 27% 31% 21% 3	671
	11th to 20th	Day	14% 8% 23% 33% 18% 5%	583
	21st to end	Day	13% 6% 26% 34% 17% 5%	532
August	1st to 10th	Day	14% 7% 20% 33% 19% 7%	486
	11th to 20th	Day	15% 5% 19% 33% 20% 9%	479
	21st to end	Day	16% 7% 24% 30% 17% 6%	539
September	1st to 10th	Day	15% 9% 24% 28% 18% 7%	490
	11th to 20th	Day	13% 7% 23% 26% 23% 9%	490
	21st to end	Day	21% 8% 23% 26% 20% 3	490
October	1st to 10th	Day	27% 13% 26% 17% 14% 4	490
	11th to 20th	Day	25% 19% 31% 18% 7% 1	490
	21st to end	Day	36% 16% 30% 14% 4	515
November	1st to 10th	Day	27% 20% 30% 19% 4	223
	11th to 20th	Day	24% 23% 35% 16% 2	180
	21st to end	Day	31% 19% 37% 14%	180
December	1st to 10th	Day	32% 21% 30% 13% 3 1	180
	11th to 20th	Day	35% 24% 27% 11% 2 1	180
	21st to end	Day	33% 22% 31% 12% 2	198
January	1st to 10th	Night	28% 18% 30% 18% 5% 1	950
	11th to 20th	Night	31% 15% 31% 19% 5% 1	795
	21st to end	Night	22% 10% 32% 26% 9% 1	836
February	1st to 10th	Night	24% 18% 32% 22% 4	760
	11th to 20th	Night	22% 13% 34% 24% 6%	743
	21st to end	Night	25% 17% 31% 21% 6%	628
March	1st to 10th	Night	21% 14% 36% 25% 5%	760
	11th to 20th	Night	18% 16% 34% 25% 6% 1	760
	21st to end	Night	21% 9% 33% 27% 10%	836
April	1st to 10th	Night	27% 11% 30% 26% 5%	760
	11th to 20th	Night	24% 11% 27% 26% 11% 1	630
	21st to end	Night	24% 9% 28% 26% 13%	570
May	1st to 10th	Night	20% 6% 22% 37% 13% 2	570
	11th to 20th	Night	17% 6% 25% 38% 13% 1	374
	21st to end	Night	12% 5% 25% 39% 18%	411
June	1st to 10th	Night	17% 6% 25% 37% 14% 1	380
	11th to 20th	Night	14% 7% 19% 42% 16% 1	380
	21st to end	Night	19% 5% 22% 32% 22% 1	380
July	1st to 10th	Night	10% 5% 18% 40% 25% 3	370
	11th to 20th	Night	13% 4 23% 31% 27% 2	368
	21st to end	Night	12% 4 23% 36% 24% 2	566
August	1st to 10th	Night	12% 5% 17% 36% 27% 3	567
	11th to 20th	Night	12% 3 18% 35% 26% 5%	564
	21st to end	Night	16% 5% 23% 28% 24% 4	665
September	1st to 10th	Night	14% 6% 23% 30% 21% 5%	760
	11th to 20th	Night	14% 6% 21% 31% 22% 5%	760
	21st to end	Night	20% 9% 19% 30% 18% 4	760
October	1st to 10th	Night	23% 12% 26% 23% 15% 1	760
	11th to 20th	Night	32% 13% 24% 22% 8% 2	760
	21st to end	Night	33% 16% 29% 19% 3	836
November	1st to 10th	Night	32% 12% 27% 19% 10%	755
	11th to 20th	Night	29% 19% 31% 16% 5%	760
	21st to end	Night	37% 14% 31% 15% 3	760
December	1st to 10th	Night	36% 20% 28% 13% 3	760
	11th to 20th	Night	29% 20% 34% 13% 4	760
	21st to end	Night	33% 14% 31% 19% 2	1007

Page generated at 2024-11-01 22:47:36. Version ac07

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