Port Crescent State Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Port Crescent State Park clear sky chart from 2005-11-06 to 2026-08-15.

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	12% 9% 4 9% 5% 5% 5% 4 6% 7% 35%	143286
	Night	13% 11% 4 11% 6% 5% 5% 3 5% 6% 30%	138789
Transparency	Day	48% 4 12% 23% 12% 1	146825
	Night	52% 4 11% 21% 11% 1	143322
Seeing	Day	18% 10% 29% 25% 13% 5%	17770
	Night	20% 10% 29% 28% 12% 2	27184

By Month

Percentage Cloud Cover SE (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% 14% 9% 23% 8% 5% 5% 3 4 3 13%	4691
	11th to 20th	Day	9% 17% 8% 19% 14% 7% 4 4 4 4 10%	4710
	21st to end	Day	13% 14% 6% 11% 8% 6% 6% 4 6% 6% 20%	5510
February	1st to 10th	Day	12% 15% 4 12% 8% 6% 5% 4 5% 6% 23%	1890
	11th to 20th	Day	11% 12% 5% 11% 9% 7% 6% 4 6% 6% 24%	1932
	21st to end	Day	13% 12% 3 10% 6% 6% 5% 4 6% 8% 26%	1730
March	1st to 10th	Day	13% 10% 3 9% 7% 5% 4 4 5% 6% 34%	4709
	11th to 20th	Day	11% 12% 5% 10% 5% 5% 5% 4 7% 9% 29%	5090
	21st to end	Day	16% 11% 5% 11% 6% 5% 5% 3 5% 6% 28%	5586
April	1st to 10th	Day	16% 11% 3 8% 5% 4 4 4 6% 8% 31%	2440
	11th to 20th	Day	16% 9% 3 6% 4 4 4 4 5% 7% 38%	2702
	21st to end	Day	14% 8% 4 7% 5% 5% 4 4 5% 7% 37%	2730
May	1st to 10th	Day	12% 7% 3 7% 5% 5% 5% 4 6% 8% 37%	7616
	11th to 20th	Day	11% 7% 3 7% 5% 5% 5% 4 6% 8% 39%	7626
	21st to end	Day	14% 7% 2 5% 3 3 3 3 5% 6% 48%	8973
June	1st to 10th	Day	10% 6% 2 5% 5% 4 5% 5% 7% 8% 44%	3150
	11th to 20th	Day	10% 5% 2 6% 5% 4 5% 5% 7% 9% 44%	3150
	21st to end	Day	10% 6% 2 5% 4 4 5% 4 6% 9% 44%	3150
July	1st to 10th	Day	10% 6% 2 6% 4 4 5% 4 6% 10% 43%	8582
	11th to 20th	Day	7% 4 2 5% 4 4 4 3 7% 9% 51%	8280
	21st to end	Day	8% 4 2 6% 4 4 4 4 6% 8% 50%	8659
August	1st to 10th	Day	9% 5% 2 6% 4 5% 5% 4 8% 10% 42%	4364
	11th to 20th	Day	12% 6% 2 6% 4 5% 5% 5% 6% 8% 44%	4226
	21st to end	Day	9% 6% 2 6% 4 4 5% 4 6% 8% 45%	4675
September	1st to 10th	Day	11% 6% 2 7% 4 4 4 4 7% 8% 44%	2291
	11th to 20th	Day	13% 6% 2 6% 2 3 4 3 6% 8% 47%	2200
	21st to end	Day	15% 7% 3 6% 4 5% 5% 4 5% 7% 38%	2200
October	1st to 10th	Day	16% 8% 3 6% 4 4 4 4 5% 7% 40%	2116
	11th to 20th	Day	21% 11% 4 8% 5% 5% 5% 3 4 6% 29%	2000
	21st to end	Day	22% 12% 3 9% 5% 5% 5% 4 6% 7% 22%	2022
November	1st to 10th	Day	14% 15% 4 10% 5% 6% 4 3 5% 7% 28%	1852
	11th to 20th	Day	15% 16% 4 9% 6% 5% 6% 4 6% 7% 21%	1825
	21st to end	Day	17% 20% 6% 13% 6% 5% 4 3 5% 5% 16%	1680
December	1st to 10th	Day	14% 21% 12% 14% 8% 6% 5% 3 4 4 10%	2657
	11th to 20th	Day	14% 19% 7% 15% 10% 7% 5% 3 4 4 13%	2695
	21st to end	Day	25% 22% 6% 15% 6% 5% 4 2 3 4 9%	3577
January	1st to 10th	Night	14% 13% 7% 22% 8% 5% 4 3 4 4 15%	8232
	11th to 20th	Night	9% 16% 8% 18% 12% 7% 5% 3 5% 4 12%	8280
	21st to end	Night	10% 13% 6% 13% 7% 7% 6% 4 5% 6% 23%	8682
February	1st to 10th	Night	12% 16% 5% 12% 7% 6% 5% 4 6% 6% 22%	2730
	11th to 20th	Night	13% 14% 5% 11% 6% 5% 4 3 5% 6% 27%	2572
	21st to end	Night	14% 14% 4 11% 6% 6% 5% 4 5% 5% 26%	2076
March	1st to 10th	Night	13% 11% 3 8% 6% 4 4 3 5% 7% 37%	5363
	11th to 20th	Night	9% 10% 4 10% 5% 5% 5% 4 6% 8% 34%	5090
	21st to end	Night	16% 11% 4 10% 6% 5% 4 3 4 5% 32%	5588
April	1st to 10th	Night	17% 13% 3 8% 5% 4 4 3 5% 6% 33%	2197
	11th to 20th	Night	17% 8% 2 7% 5% 4 4 3 6% 8% 37%	1867
	21st to end	Night	17% 9% 4 8% 4 5% 3 3 6% 6% 35%	1890
May	1st to 10th	Night	12% 9% 3 9% 5% 5% 5% 4 5% 8% 37%	5237
	11th to 20th	Night	14% 8% 3 8% 5% 4 4 3 6% 7% 38%	5234
	21st to end	Night	17% 5% 2 6% 4 4 4 3 5% 7% 44%	5187
June	1st to 10th	Night	13% 6% 3 7% 5% 4 3 4 6% 8% 42%	1470
	11th to 20th	Night	10% 5% 1 7% 5% 5% 5% 4 6% 9% 43%	1470
	21st to end	Night	9% 7% 3 6% 6% 4 4 4 6% 9% 43%	1470
July	1st to 10th	Night	8% 6% 3 7% 4 4 4 4 6% 8% 44%	4400
	11th to 20th	Night	7% 4 2 4 4 4 5% 4 7% 9% 51%	4707
	21st to end	Night	9% 5% 2 6% 4 4 4 4 6% 8% 48%	5417
August	1st to 10th	Night	9% 5% 2 6% 4 4 5% 4 6% 9% 46%	3005
	11th to 20th	Night	11% 6% 2 5% 3 4 4 4 7% 10% 45%	2911
	21st to end	Night	7% 5% 2 7% 5% 5% 5% 4 7% 8% 45%	3223
September	1st to 10th	Night	11% 6% 2 6% 5% 3 5% 3 5% 7% 47%	2086
	11th to 20th	Night	11% 6% 2 5% 4 3 4 3 5% 6% 52%	2200
	21st to end	Night	15% 8% 3 7% 4 4 4 3 5% 7% 39%	2200
October	1st to 10th	Night	16% 7% 3 7% 5% 4 4 4 5% 7% 40%	2283
	11th to 20th	Night	21% 13% 3 8% 4 5% 3 3 4 6% 30%	2400
	21st to end	Night	22% 13% 3 9% 5% 4 4 4 4 5% 26%	2815
November	1st to 10th	Night	15% 14% 4 8% 5% 4 4 3 5% 6% 32%	2666
	11th to 20th	Night	15% 16% 6% 13% 7% 5% 5% 4 5% 5% 20%	2793
	21st to end	Night	21% 19% 6% 12% 5% 5% 4 3 4 4 18%	2940
December	1st to 10th	Night	14% 19% 9% 17% 6% 5% 5% 3 4 6% 12%	4738
	11th to 20th	Night	12% 17% 7% 16% 9% 7% 5% 4 4 5% 15%	5732
	21st to end	Night	22% 20% 8% 13% 6% 5% 5% 3 4 4 10%	7638

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 9% 10% 4 1	4692
	11th to 20th	Day	77% 4 4 10% 6%	4710
	21st to end	Day	64% 4 10% 11% 11%	5510
February	1st to 10th	Day	61% 5% 9% 19% 6%	1890
	11th to 20th	Day	61% 4 10% 16% 8% 1	1941
	21st to end	Day	56% 3 12% 20% 8% 1	1730
March	1st to 10th	Day	52% 4 14% 20% 9% 2	4709
	11th to 20th	Day	53% 3 14% 21% 8% 1	5090
	21st to end	Day	59% 3 11% 17% 9% 1	5586
April	1st to 10th	Day	53% 4 12% 20% 11% 1	2440
	11th to 20th	Day	47% 3 11% 22% 15% 1	2702
	21st to end	Day	48% 3 13% 22% 12% 2	2730
May	1st to 10th	Day	44% 3 11% 25% 14% 3	7651
	11th to 20th	Day	43% 4 11% 26% 15% 1	7630
	21st to end	Day	38% 2 8% 26% 20% 5%	8988
June	1st to 10th	Day	37% 4 12% 28% 17% 1	3150
	11th to 20th	Day	36% 4 13% 28% 17% 2	3150
	21st to end	Day	37% 5% 13% 28% 15% 1	3150
July	1st to 10th	Day	37% 4 15% 27% 15% 2	8512
	11th to 20th	Day	30% 4 13% 37% 16% 1	8205
	21st to end	Day	32% 4 14% 31% 18% 1	8469
August	1st to 10th	Day	36% 5% 14% 29% 14% 1	4351
	11th to 20th	Day	38% 4 18% 30% 10% 1	4265
	21st to end	Day	37% 4 14% 32% 13% 1	4674
September	1st to 10th	Day	38% 5% 15% 30% 11% 1	2291
	11th to 20th	Day	35% 4 14% 32% 14%	2200
	21st to end	Day	46% 4 14% 24% 11%	2200
October	1st to 10th	Day	35% 3 11% 37% 12% 2	3441
	11th to 20th	Day	50% 3 11% 23% 13%	3240
	21st to end	Day	54% 4 12% 23% 8%	3246
November	1st to 10th	Day	56% 4 11% 21% 8% 1	1852
	11th to 20th	Day	61% 5% 13% 13% 8%	1825
	21st to end	Day	70% 3 10% 13% 3	1680
December	1st to 10th	Day	76% 5% 10% 8% 1	2657
	11th to 20th	Day	73% 3 9% 11% 3	2691
	21st to end	Day	81% 3 6% 7% 3	3577
January	1st to 10th	Night	70% 4 10% 11% 5%	8233
	11th to 20th	Night	72% 3 8% 10% 6% 1	8280
	21st to end	Night	60% 4 9% 16% 11%	8682
February	1st to 10th	Night	61% 4 9% 19% 7% 1	2730
	11th to 20th	Night	57% 4 10% 20% 8% 1	2574
	21st to end	Night	60% 3 11% 18% 8%	2076
March	1st to 10th	Night	48% 2 15% 24% 10% 1	5363
	11th to 20th	Night	48% 3 17% 22% 9% 1	5090
	21st to end	Night	54% 3 10% 20% 11% 1	5588
April	1st to 10th	Night	53% 3 8% 21% 14% 2	2197
	11th to 20th	Night	46% 3 9% 22% 18% 2	1867
	21st to end	Night	49% 3 8% 20% 16% 3	1890
May	1st to 10th	Night	47% 3 9% 20% 17% 4	5264
	11th to 20th	Night	46% 4 10% 25% 15% 1	5235
	21st to end	Night	41% 2 7% 26% 18% 5%	5194
June	1st to 10th	Night	40% 3 8% 28% 19% 2	1470
	11th to 20th	Night	37% 5% 13% 22% 20% 2	1470
	21st to end	Night	38% 3 12% 26% 18% 2	1470
July	1st to 10th	Night	37% 4 14% 23% 18% 4	4363
	11th to 20th	Night	28% 4 12% 36% 18% 1	4662
	21st to end	Night	35% 4 14% 28% 19% 1	5295
August	1st to 10th	Night	35% 4 13% 31% 15% 1	2994
	11th to 20th	Night	34% 4 15% 31% 14% 2	2938
	21st to end	Night	34% 5% 13% 33% 14% 1	3223
September	1st to 10th	Night	37% 4 11% 30% 15% 1	2086
	11th to 20th	Night	33% 3 11% 35% 16% 1	2200
	21st to end	Night	44% 3 12% 29% 11% 1	2200
October	1st to 10th	Night	30% 4 10% 34% 21% 1	3738
	11th to 20th	Night	50% 2 8% 25% 15%	3899
	21st to end	Night	51% 3 11% 26% 9%	4541
November	1st to 10th	Night	52% 4 10% 23% 10% 1	2666
	11th to 20th	Night	63% 4 12% 15% 6% 1	2793
	21st to end	Night	68% 4 12% 13% 3	2940
December	1st to 10th	Night	71% 4 12% 10% 3	4738
	11th to 20th	Night	69% 3 10% 12% 6%	5735
	21st to end	Night	76% 3 8% 8% 4	7638

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	20% 15% 42% 16% 6% 1	330
	11th to 20th	Day	20% 19% 39% 16% 5% 1	330
	21st to end	Day	23% 12% 40% 20% 4 1	363
February	1st to 10th	Day	20% 21% 37% 16% 5% 1	330
	11th to 20th	Day	20% 20% 42% 15% 2	330
	21st to end	Day	22% 25% 34% 16% 3	273
March	1st to 10th	Day	23% 19% 39% 15% 3 1	381
	11th to 20th	Day	22% 16% 32% 22% 6% 2	540
	21st to end	Day	26% 12% 33% 21% 6% 1	594
April	1st to 10th	Day	24% 15% 34% 20% 6% 1	540
	11th to 20th	Day	27% 13% 28% 18% 11% 3	532
	21st to end	Day	23% 9% 34% 24% 8% 3	540
May	1st to 10th	Day	19% 13% 33% 23% 10% 2	543
	11th to 20th	Day	17% 10% 29% 24% 14% 6%	567
	21st to end	Day	15% 6% 30% 29% 15% 5%	691
June	1st to 10th	Day	13% 6% 33% 29% 14% 3	780
	11th to 20th	Day	13% 7% 31% 33% 13% 4	780
	21st to end	Day	15% 5% 30% 31% 14% 4	780
July	1st to 10th	Day	10% 4 23% 33% 22% 7%	771
	11th to 20th	Day	12% 4 24% 35% 17% 7%	768
	21st to end	Day	10% 3 24% 36% 20% 8%	735
August	1st to 10th	Day	12% 3 19% 30% 23% 12%	566
	11th to 20th	Day	11% 2 18% 32% 23% 13%	535
	21st to end	Day	15% 4 19% 30% 23% 8%	583
September	1st to 10th	Day	13% 5% 25% 27% 19% 11%	530
	11th to 20th	Day	12% 4 17% 25% 25% 17%	530
	21st to end	Day	19% 6% 23% 24% 19% 8%	530
October	1st to 10th	Day	21% 8% 25% 22% 16% 7%	530
	11th to 20th	Day	27% 11% 29% 25% 6% 1	530
	21st to end	Day	29% 12% 33% 21% 5% 1	405
November	1st to 10th	Day	22% 16% 34% 19% 7% 2	330
	11th to 20th	Day	23% 18% 33% 20% 6% 1	295
	21st to end	Day	23% 19% 35% 20% 4	220
December	1st to 10th	Day	25% 15% 35% 19% 5%	220
	11th to 20th	Day	27% 22% 32% 14% 4 1	220
	21st to end	Day	32% 16% 33% 15% 4	248
January	1st to 10th	Night	22% 14% 36% 21% 6% 1	1050
	11th to 20th	Night	22% 16% 35% 21% 5% 1	1050
	21st to end	Night	17% 12% 37% 25% 8%	1024
February	1st to 10th	Night	21% 15% 37% 23% 4	840
	11th to 20th	Night	22% 14% 35% 23% 7%	823
	21st to end	Night	22% 16% 37% 22% 4	692
March	1st to 10th	Night	18% 12% 36% 25% 8% 1	840
	11th to 20th	Night	18% 14% 38% 23% 6%	840
	21st to end	Night	24% 11% 29% 27% 8% 1	924
April	1st to 10th	Night	23% 12% 36% 22% 7%	728
	11th to 20th	Night	22% 11% 31% 23% 11% 2	623
	21st to end	Night	23% 8% 25% 34% 9% 1	630
May	1st to 10th	Night	16% 5% 28% 39% 10% 2	630
	11th to 20th	Night	19% 6% 24% 34% 16% 1	621
	21st to end	Night	15% 3 28% 34% 18% 1	563
June	1st to 10th	Night	15% 5% 24% 39% 17%	420
	11th to 20th	Night	14% 3 29% 37% 15% 1	420
	21st to end	Night	13% 3 25% 38% 19% 2	420
July	1st to 10th	Night	10% 1 18% 45% 25% 1	503
	11th to 20th	Night	11% 2 17% 39% 25% 5%	612
	21st to end	Night	9% 1 19% 45% 23% 3	690
August	1st to 10th	Night	11% 2 11% 42% 31% 3	627
	11th to 20th	Night	12% 2 14% 35% 31% 6%	606
	21st to end	Night	13% 3 18% 37% 25% 4	660
September	1st to 10th	Night	13% 4 22% 32% 23% 6%	718
	11th to 20th	Night	13% 3 17% 34% 26% 8%	800
	21st to end	Night	17% 6% 19% 33% 17% 6%	800
October	1st to 10th	Night	19% 6% 27% 29% 17% 2	800
	11th to 20th	Night	28% 11% 26% 28% 7% 1	800
	21st to end	Night	29% 8% 30% 28% 5% 1	880
November	1st to 10th	Night	23% 14% 29% 24% 10% 1	820
	11th to 20th	Night	23% 15% 32% 22% 8%	840
	21st to end	Night	30% 14% 32% 20% 4	840
December	1st to 10th	Night	24% 16% 36% 18% 6%	845
	11th to 20th	Night	23% 16% 37% 18% 4 1	1050
	21st to end	Night	30% 13% 34% 20% 3	1155

Page generated at 2026-08-12 03:37:20. Version ac07

Copyright © 2026 Attilla Danko.