Long Point Provincial Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Long Point Provincial Park clear sky chart from 2005-11-06 to 2025-02-06.

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	14% 10% 4 9% 6% 5% 5% 4 5% 7% 32%	108609
	Night	16% 11% 4 9% 6% 5% 5% 4 5% 6% 29%	109616
Transparency	Day	49% 8% 14% 19% 10% 1	112252
	Night	54% 7% 12% 17% 10% 1	114137
Seeing	Day	17% 7% 22% 29% 20% 5%	14727
	Night	21% 9% 25% 27% 15% 3	24414

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	14% 18% 9% 15% 7% 6% 7% 2 4 3 14%	3799
	11th to 20th	Day	11% 21% 9% 24% 11% 5% 5% 3 3 3 6%	4026
	21st to end	Day	19% 15% 6% 14% 7% 8% 6% 4 3 4 15%	4466
February	1st to 10th	Day	17% 16% 5% 12% 7% 6% 6% 4 5% 6% 18%	1755
	11th to 20th	Day	15% 12% 7% 11% 7% 6% 6% 3 5% 5% 23%	1663
	21st to end	Day	20% 12% 3 9% 6% 4 6% 4 5% 5% 24%	1527
March	1st to 10th	Day	19% 10% 4 9% 6% 5% 5% 3 5% 6% 27%	3420
	11th to 20th	Day	10% 13% 4 8% 6% 6% 5% 4 6% 8% 31%	3480
	21st to end	Day	18% 8% 3 7% 6% 6% 4 4 5% 6% 34%	3815
April	1st to 10th	Day	15% 10% 3 8% 5% 5% 4 4 5% 6% 33%	2193
	11th to 20th	Day	17% 9% 3 8% 3 5% 4 3 6% 8% 35%	2361
	21st to end	Day	18% 9% 2 6% 4 4 4 4 6% 7% 36%	2470
May	1st to 10th	Day	18% 7% 3 8% 6% 5% 5% 4 6% 7% 32%	4108
	11th to 20th	Day	15% 9% 3 8% 5% 4 5% 4 7% 8% 32%	4162
	21st to end	Day	9% 5% 2 6% 5% 5% 5% 4 6% 9% 46%	4837
June	1st to 10th	Day	11% 6% 2 6% 4 5% 5% 4 6% 8% 40%	2660
	11th to 20th	Day	10% 6% 2 6% 5% 4 5% 5% 6% 9% 41%	2660
	21st to end	Day	10% 5% 2 5% 4 4 4 4 6% 11% 45%	2660
July	1st to 10th	Day	7% 5% 2 6% 4 4 5% 4 7% 10% 46%	4440
	11th to 20th	Day	10% 5% 2 5% 4 4 4 4 6% 11% 46%	4202
	21st to end	Day	6% 4 2 5% 4 5% 5% 4 8% 10% 46%	4466
August	1st to 10th	Day	15% 5% 2 5% 4 4 4 4 6% 10% 42%	4104
	11th to 20th	Day	11% 6% 2 6% 4 5% 5% 4 7% 10% 39%	4044
	21st to end	Day	8% 6% 2 6% 4 4 5% 5% 6% 9% 44%	4404
September	1st to 10th	Day	11% 6% 2 6% 4 4 6% 4 5% 7% 45%	2280
	11th to 20th	Day	8% 5% 2 5% 5% 4 4 4 6% 8% 49%	2091
	21st to end	Day	16% 6% 3 7% 5% 5% 5% 4 5% 7% 37%	2090
October	1st to 10th	Day	14% 7% 3 7% 6% 5% 5% 4 6% 7% 37%	1905
	11th to 20th	Day	20% 8% 3 8% 7% 5% 5% 4 6% 6% 28%	1900
	21st to end	Day	22% 10% 4 8% 6% 5% 4 3 6% 7% 23%	2090
November	1st to 10th	Day	14% 10% 3 8% 5% 5% 4 4 6% 6% 36%	1785
	11th to 20th	Day	17% 11% 5% 9% 7% 5% 3 5% 5% 6% 27%	1600
	21st to end	Day	22% 16% 4 11% 6% 6% 4 2 6% 6% 17%	1600
December	1st to 10th	Day	19% 19% 6% 13% 10% 9% 5% 3 3 5% 9%	2600
	11th to 20th	Day	21% 19% 5% 13% 5% 7% 6% 3 4 4 13%	2986
	21st to end	Day	26% 19% 5% 11% 6% 5% 4 4 4 5% 12%	3960
January	1st to 10th	Night	16% 16% 7% 14% 7% 6% 8% 3 4 4 16%	6142
	11th to 20th	Night	12% 19% 8% 19% 12% 6% 4 3 3 3 11%	5859
	21st to end	Night	20% 16% 7% 16% 5% 6% 5% 4 4 4 13%	6490
February	1st to 10th	Night	17% 17% 4 12% 7% 5% 5% 4 4 5% 21%	2536
	11th to 20th	Night	16% 14% 3 10% 7% 5% 5% 5% 5% 6% 23%	2403
	21st to end	Night	19% 12% 4 9% 7% 5% 4 4 5% 6% 24%	1925
March	1st to 10th	Night	19% 10% 4 7% 5% 5% 4 3 4 6% 32%	3419
	11th to 20th	Night	15% 10% 3 6% 5% 4 5% 4 5% 8% 35%	3479
	21st to end	Night	16% 10% 3 7% 4 4 4 3 5% 5% 39%	3817
April	1st to 10th	Night	19% 10% 3 7% 6% 4 4 4 4 7% 32%	1986
	11th to 20th	Night	18% 8% 3 6% 5% 4 4 3 6% 7% 35%	1784
	21st to end	Night	15% 6% 3 7% 5% 5% 6% 4 6% 7% 36%	1710
May	1st to 10th	Night	20% 9% 3 7% 4 3 4 4 5% 7% 36%	2833
	11th to 20th	Night	12% 8% 3 9% 5% 5% 5% 4 6% 7% 35%	2727
	21st to end	Night	10% 6% 2 6% 4 3 3 4 7% 9% 46%	2738
June	1st to 10th	Night	11% 7% 3 5% 5% 5% 4 4 7% 8% 41%	1520
	11th to 20th	Night	10% 5% 2 6% 6% 4 5% 4 7% 9% 42%	1520
	21st to end	Night	11% 5% 2 6% 4 4 5% 4 6% 9% 44%	1520
July	1st to 10th	Night	7% 5% 2 6% 4 4 4 4 5% 10% 48%	2520
	11th to 20th	Night	8% 5% 2 6% 5% 4 4 4 6% 9% 48%	2740
	21st to end	Night	6% 5% 2 7% 4 5% 4 5% 7% 9% 47%	3087
August	1st to 10th	Night	12% 5% 2 6% 5% 4 4 4 6% 10% 42%	2825
	11th to 20th	Night	12% 5% 3 6% 4 4 4 4 6% 8% 44%	2785
	21st to end	Night	7% 5% 2 5% 5% 5% 4 4 6% 9% 48%	3220
September	1st to 10th	Night	12% 7% 2 6% 4 3 4 3 5% 8% 46%	1900
	11th to 20th	Night	11% 4 1 5% 3 4 4 3 4 7% 52%	2085
	21st to end	Night	16% 7% 3 8% 5% 4 4 4 5% 6% 38%	2090
October	1st to 10th	Night	16% 7% 2 6% 4 4 4 4 5% 7% 40%	2274
	11th to 20th	Night	19% 9% 3 8% 7% 4 4 3 5% 7% 31%	2280
	21st to end	Night	23% 8% 3 8% 5% 4 4 3 5% 7% 30%	2508
November	1st to 10th	Night	17% 7% 3 7% 5% 6% 4 3 5% 7% 37%	2510
	11th to 20th	Night	18% 13% 4 8% 6% 6% 6% 3 5% 8% 25%	2800
	21st to end	Night	21% 15% 4 9% 7% 6% 5% 3 5% 6% 19%	2800
December	1st to 10th	Night	17% 19% 7% 12% 8% 7% 5% 3 4 5% 13%	4580
	11th to 20th	Night	21% 19% 5% 14% 6% 5% 6% 3 4 5% 12%	5208
	21st to end	Night	24% 19% 5% 11% 6% 4 4 3 4 5% 14%	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	75% 7% 7% 6% 5%	3800
	11th to 20th	Day	86% 5% 5% 4 1	4060
	21st to end	Day	73% 8% 9% 7% 3 1	4466
February	1st to 10th	Day	66% 7% 12% 11% 3	1755
	11th to 20th	Day	62% 6% 12% 13% 6%	1672
	21st to end	Day	59% 6% 12% 16% 5% 1	1527
March	1st to 10th	Day	53% 9% 12% 21% 4	3423
	11th to 20th	Day	46% 10% 21% 16% 6% 1	3480
	21st to end	Day	48% 9% 13% 20% 9% 1	3815
April	1st to 10th	Day	48% 6% 15% 19% 12%	2193
	11th to 20th	Day	46% 6% 13% 21% 13% 1	2361
	21st to end	Day	46% 8% 13% 18% 13% 2	2470
May	1st to 10th	Day	45% 10% 13% 20% 10% 2	4120
	11th to 20th	Day	45% 12% 14% 20% 8% 1	4166
	21st to end	Day	33% 9% 15% 22% 16% 6%	4837
June	1st to 10th	Day	37% 10% 13% 24% 14% 1	2660
	11th to 20th	Day	36% 10% 15% 23% 16% 1	2660
	21st to end	Day	32% 8% 16% 27% 15% 1	2660
July	1st to 10th	Day	31% 6% 15% 28% 17% 3	4370
	11th to 20th	Day	30% 6% 15% 30% 17% 1	4130
	21st to end	Day	31% 7% 19% 23% 19% 1	4324
August	1st to 10th	Day	37% 7% 17% 25% 13% 1	4091
	11th to 20th	Day	37% 8% 19% 26% 9% 1	4083
	21st to end	Day	34% 7% 14% 31% 13% 1	4404
September	1st to 10th	Day	36% 8% 17% 24% 13% 1	2280
	11th to 20th	Day	32% 8% 16% 28% 16%	2091
	21st to end	Day	46% 8% 14% 22% 10% 1	2090
October	1st to 10th	Day	35% 7% 17% 25% 16% 1	3165
	11th to 20th	Day	42% 7% 16% 23% 11%	3140
	21st to end	Day	47% 6% 17% 25% 6%	3428
November	1st to 10th	Day	49% 8% 14% 20% 8% 2	1785
	11th to 20th	Day	57% 8% 13% 13% 8% 1	1600
	21st to end	Day	70% 8% 10% 9% 3	1600
December	1st to 10th	Day	82% 5% 7% 5% 1	2600
	11th to 20th	Day	75% 7% 10% 6% 2	2986
	21st to end	Day	76% 6% 9% 7% 2	3960
January	1st to 10th	Night	71% 10% 9% 8% 2	6142
	11th to 20th	Night	80% 6% 7% 5% 2	5900
	21st to end	Night	75% 6% 7% 8% 4	6490
February	1st to 10th	Night	66% 7% 12% 11% 3	2536
	11th to 20th	Night	61% 8% 11% 15% 5%	2405
	21st to end	Night	59% 7% 13% 14% 6% 1	1925
March	1st to 10th	Night	53% 7% 13% 19% 7%	3429
	11th to 20th	Night	44% 9% 18% 18% 10% 1	3480
	21st to end	Night	45% 7% 13% 19% 14% 2	3817
April	1st to 10th	Night	52% 6% 11% 18% 11% 2	1986
	11th to 20th	Night	47% 6% 12% 19% 14% 2	1784
	21st to end	Night	46% 8% 11% 19% 13% 3	1710
May	1st to 10th	Night	47% 7% 11% 19% 12% 4	2840
	11th to 20th	Night	45% 9% 15% 20% 9% 2	2728
	21st to end	Night	31% 9% 15% 23% 20% 3	2739
June	1st to 10th	Night	38% 9% 13% 23% 14% 3	1520
	11th to 20th	Night	37% 8% 13% 22% 18% 2	1520
	21st to end	Night	37% 9% 13% 23% 17% 1	1520
July	1st to 10th	Night	35% 6% 12% 23% 20% 6%	2480
	11th to 20th	Night	33% 5% 13% 30% 17% 2	2690
	21st to end	Night	34% 6% 17% 22% 20% 2	2988
August	1st to 10th	Night	38% 7% 12% 27% 14% 2	2814
	11th to 20th	Night	38% 7% 16% 28% 10% 1	2812
	21st to end	Night	31% 7% 14% 32% 14% 1	3220
September	1st to 10th	Night	37% 8% 12% 24% 16% 2	1900
	11th to 20th	Night	34% 5% 14% 28% 19%	2085
	21st to end	Night	47% 7% 11% 22% 12% 1	2090
October	1st to 10th	Night	35% 6% 9% 27% 22% 2	3794
	11th to 20th	Night	46% 4 13% 23% 13%	3779
	21st to end	Night	42% 5% 16% 23% 13% 1	4120
November	1st to 10th	Night	50% 7% 12% 20% 11% 1	2510
	11th to 20th	Night	60% 8% 10% 13% 7% 1	2800
	21st to end	Night	67% 9% 11% 11% 2	2800
December	1st to 10th	Night	76% 6% 10% 6% 1	4580
	11th to 20th	Night	77% 7% 8% 6% 1	5208
	21st to end	Night	73% 7% 9% 8% 3	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	24% 14% 33% 19% 9% 1	243
	11th to 20th	Day	26% 14% 34% 19% 5% 1	300
	21st to end	Day	21% 12% 35% 25% 7%	330
February	1st to 10th	Day	23% 12% 28% 32% 5%	285
	11th to 20th	Day	20% 13% 36% 27% 4	270
	21st to end	Day	20% 18% 34% 24% 4	225
March	1st to 10th	Day	20% 9% 28% 33% 10%	448
	11th to 20th	Day	20% 9% 30% 33% 7% 2	460
	21st to end	Day	25% 8% 28% 27% 11% 1	506
April	1st to 10th	Day	17% 7% 31% 35% 9% 2	460
	11th to 20th	Day	19% 10% 26% 27% 13% 4	452
	21st to end	Day	21% 6% 23% 37% 12% 1	460
May	1st to 10th	Day	23% 5% 19% 33% 17% 3	463
	11th to 20th	Day	17% 2 20% 30% 24% 6%	487
	21st to end	Day	12% 3 13% 31% 31% 9%	529
June	1st to 10th	Day	12% 3 21% 36% 23% 4	490
	11th to 20th	Day	12% 3 18% 33% 28% 6%	490
	21st to end	Day	12% 4 15% 38% 27% 4	490
July	1st to 10th	Day	6% 1 13% 32% 34% 13%	485
	11th to 20th	Day	12% 4 11% 31% 31% 10%	484
	21st to end	Day	7% 2 12% 38% 35% 6%	532
August	1st to 10th	Day	12% 2 9% 32% 34% 11%	486
	11th to 20th	Day	12% 2 12% 29% 37% 8%	479
	21st to end	Day	12% 3 13% 29% 35% 8%	539
September	1st to 10th	Day	12% 3 18% 28% 26% 14%	490
	11th to 20th	Day	9% 4 11% 25% 33% 19%	490
	21st to end	Day	16% 7% 21% 26% 23% 8%	490
October	1st to 10th	Day	15% 8% 20% 28% 20% 10%	490
	11th to 20th	Day	20% 12% 26% 27% 12% 3	490
	21st to end	Day	29% 10% 25% 24% 11%	539
November	1st to 10th	Day	21% 12% 27% 25% 14% 2	325
	11th to 20th	Day	25% 16% 28% 22% 8% 2	200
	21st to end	Day	31% 13% 30% 23% 4	200
December	1st to 10th	Day	30% 18% 28% 19% 6% 1	200
	11th to 20th	Day	30% 18% 31% 19% 3	200
	21st to end	Day	26% 17% 30% 20% 6%	220
January	1st to 10th	Night	28% 16% 35% 16% 6%	800
	11th to 20th	Night	29% 15% 32% 22% 4	800
	21st to end	Night	22% 12% 36% 24% 6%	880
February	1st to 10th	Night	27% 9% 33% 26% 4	781
	11th to 20th	Night	22% 10% 35% 28% 4	743
	21st to end	Night	24% 10% 36% 26% 5%	628
March	1st to 10th	Night	20% 7% 32% 31% 9%	760
	11th to 20th	Night	21% 7% 34% 29% 9% 1	760
	21st to end	Night	20% 8% 28% 32% 10% 2	836
April	1st to 10th	Night	21% 8% 29% 33% 9% 1	760
	11th to 20th	Night	20% 8% 27% 32% 12% 2	660
	21st to end	Night	18% 4 24% 40% 13% 1	570
May	1st to 10th	Night	19% 5% 23% 30% 20% 3	570
	11th to 20th	Night	18% 3 18% 36% 22% 3	515
	21st to end	Night	14% 2 13% 32% 31% 8%	411
June	1st to 10th	Night	14% 3 21% 34% 25% 3	380
	11th to 20th	Night	12% 3 16% 37% 29% 3	380
	21st to end	Night	12% 3 19% 36% 28% 3	380
July	1st to 10th	Night	7% 3 11% 37% 31% 11%	370
	11th to 20th	Night	9% 3 15% 34% 32% 7%	495
	21st to end	Night	10% 2 12% 38% 33% 5%	624
August	1st to 10th	Night	9% 2 13% 32% 37% 7%	567
	11th to 20th	Night	9% 2 15% 30% 37% 7%	564
	21st to end	Night	11% 2 16% 33% 30% 8%	684
September	1st to 10th	Night	16% 5% 15% 26% 29% 9%	760
	11th to 20th	Night	13% 3 14% 27% 32% 11%	760
	21st to end	Night	17% 6% 19% 29% 21% 7%	760
October	1st to 10th	Night	19% 8% 21% 26% 21% 6%	760
	11th to 20th	Night	24% 12% 25% 26% 11% 3	760
	21st to end	Night	29% 11% 29% 23% 7% 1	836
November	1st to 10th	Night	22% 12% 26% 26% 12% 2	780
	11th to 20th	Night	25% 16% 30% 21% 6% 2	800
	21st to end	Night	31% 16% 30% 18% 5%	800
December	1st to 10th	Night	34% 18% 28% 14% 5% 1	800
	11th to 20th	Night	29% 19% 32% 17% 4	800
	21st to end	Night	30% 13% 34% 20% 3	880

Page generated at 2025-02-03 03:05:51. Version ac07

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