Point Pelee National Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Point Pelee National Park clear sky chart from 2005-11-06 to 2026-06-16.

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	13% 9% 3 8% 5% 5% 5% 4 6% 7% 35%	137183
	Night	15% 11% 4 9% 5% 5% 4 3 5% 6% 33%	134855
Transparency	Day	46% 6% 13% 21% 12% 1	140780
	Night	50% 6% 11% 19% 13% 1	139330
Seeing	Day	15% 5% 20% 31% 23% 6%	17290
	Night	19% 7% 25% 29% 16% 3	26912

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	14% 16% 6% 16% 6% 5% 4 3 6% 5% 19%	4691
	11th to 20th	Day	12% 17% 7% 16% 9% 8% 4 3 3 4 17%	5165
	21st to end	Day	18% 14% 4 12% 6% 6% 6% 4 5% 5% 19%	5780
February	1st to 10th	Day	14% 15% 5% 11% 7% 5% 4 3 5% 6% 25%	1890
	11th to 20th	Day	14% 11% 5% 12% 7% 5% 5% 3 5% 7% 25%	1948
	21st to end	Day	15% 10% 4 10% 6% 4 6% 4 6% 7% 27%	1730
March	1st to 10th	Day	16% 10% 5% 10% 5% 5% 4 3 5% 6% 32%	4805
	11th to 20th	Day	11% 9% 3 8% 6% 5% 4 4 5% 7% 37%	5090
	21st to end	Day	15% 9% 4 8% 6% 5% 5% 4 6% 7% 31%	5586
April	1st to 10th	Day	14% 8% 3 7% 6% 5% 5% 5% 6% 7% 34%	2364
	11th to 20th	Day	15% 7% 3 7% 5% 5% 5% 4 6% 7% 36%	2702
	21st to end	Day	16% 7% 3 8% 5% 4 5% 4 5% 7% 38%	2730
May	1st to 10th	Day	17% 8% 3 8% 5% 4 4 4 5% 7% 34%	7616
	11th to 20th	Day	13% 7% 3 8% 5% 5% 5% 4 6% 9% 34%	7626
	21st to end	Day	14% 6% 2 7% 4 4 4 4 6% 7% 43%	8391
June	1st to 10th	Day	10% 6% 2 6% 4 4 5% 4 7% 9% 43%	2915
	11th to 20th	Day	8% 6% 2 6% 4 4 5% 5% 7% 9% 43%	3076
	21st to end	Day	8% 5% 2 5% 5% 4 4 5% 8% 11% 43%	2908
July	1st to 10th	Day	8% 5% 2 6% 4 4 5% 4 6% 9% 48%	6360
	11th to 20th	Day	7% 5% 2 5% 4 4 5% 4 7% 9% 50%	6136
	21st to end	Day	8% 5% 2 7% 5% 4 5% 4 6% 9% 46%	6424
August	1st to 10th	Day	11% 5% 2 5% 3 3 4 3 7% 9% 46%	4234
	11th to 20th	Day	9% 5% 2 6% 5% 5% 5% 5% 7% 9% 41%	4174
	21st to end	Day	8% 5% 2 6% 4 5% 5% 4 7% 10% 44%	4675
September	1st to 10th	Day	10% 6% 2 5% 4 3 4 4 6% 8% 49%	2241
	11th to 20th	Day	8% 5% 2 5% 4 4 5% 4 6% 8% 50%	2200
	21st to end	Day	17% 6% 3 5% 4 4 4 4 6% 6% 40%	2200
October	1st to 10th	Day	12% 6% 2 7% 5% 4 4 3 6% 7% 45%	2108
	11th to 20th	Day	17% 8% 3 7% 4 4 4 3 6% 8% 36%	2000
	21st to end	Day	20% 9% 3 6% 4 4 6% 4 5% 8% 31%	2110
November	1st to 10th	Day	12% 10% 3 6% 4 5% 4 4 6% 7% 38%	1852
	11th to 20th	Day	16% 14% 4 9% 5% 4 4 3 5% 7% 30%	1890
	21st to end	Day	17% 17% 6% 8% 4 4 4 4 5% 6% 24%	1716
December	1st to 10th	Day	16% 14% 10% 15% 7% 5% 4 3 5% 4 17%	2680
	11th to 20th	Day	20% 18% 6% 10% 7% 4 4 4 4 6% 17%	3070
	21st to end	Day	24% 18% 6% 12% 6% 5% 4 3 4 4 13%	4100
January	1st to 10th	Night	15% 16% 7% 14% 6% 4 4 3 4 4 22%	8232
	11th to 20th	Night	11% 17% 8% 13% 7% 9% 5% 3 4 5% 18%	7767
	21st to end	Night	17% 15% 6% 9% 4 4 4 3 5% 6% 26%	8401
February	1st to 10th	Night	16% 13% 5% 10% 7% 5% 5% 4 5% 6% 24%	2730
	11th to 20th	Night	16% 13% 4 10% 6% 5% 6% 4 6% 6% 25%	2554
	21st to end	Night	19% 13% 4 9% 5% 4 4 3 5% 6% 28%	2076
March	1st to 10th	Night	17% 10% 3 8% 4 4 4 3 5% 5% 35%	5266
	11th to 20th	Night	10% 7% 2 7% 5% 5% 6% 4 6% 8% 41%	5090
	21st to end	Night	15% 9% 3 8% 5% 5% 4 3 5% 6% 37%	5588
April	1st to 10th	Night	16% 11% 3 8% 5% 4 5% 3 5% 6% 34%	2273
	11th to 20th	Night	16% 8% 3 7% 5% 4 5% 3 6% 7% 35%	1867
	21st to end	Night	16% 8% 2 6% 5% 5% 4 4 6% 6% 39%	1890
May	1st to 10th	Night	20% 9% 3 9% 6% 5% 5% 4 5% 6% 28%	5237
	11th to 20th	Night	14% 8% 3 8% 5% 4 4 4 5% 7% 37%	5234
	21st to end	Night	15% 6% 2 6% 4 5% 4 4 5% 7% 42%	5761
June	1st to 10th	Night	11% 6% 2 6% 4 4 5% 4 7% 7% 44%	1693
	11th to 20th	Night	10% 5% 3 5% 6% 4 5% 4 7% 8% 43%	1435
	21st to end	Night	8% 5% 2 5% 6% 5% 4 4 7% 9% 46%	1484
July	1st to 10th	Night	8% 4 2 5% 4 4 5% 5% 6% 11% 46%	3618
	11th to 20th	Night	9% 5% 2 6% 4 4 5% 4 7% 9% 45%	3827
	21st to end	Night	8% 5% 2 6% 4 4 4 4 6% 8% 49%	4427
August	1st to 10th	Night	14% 6% 2 6% 4 4 4 3 5% 8% 45%	2915
	11th to 20th	Night	9% 5% 2 6% 5% 4 5% 3 5% 7% 48%	2875
	21st to end	Night	7% 4 2 6% 5% 5% 5% 5% 6% 7% 47%	3223
September	1st to 10th	Night	10% 5% 2 6% 5% 4 4 4 5% 7% 48%	2135
	11th to 20th	Night	8% 4 2 6% 4 4 4 3 5% 7% 53%	2200
	21st to end	Night	16% 7% 2 7% 5% 5% 4 4 5% 6% 40%	2200
October	1st to 10th	Night	14% 6% 2 6% 4 4 4 3 4 7% 46%	2291
	11th to 20th	Night	19% 8% 3 7% 5% 5% 3 4 5% 6% 35%	2400
	21st to end	Night	22% 9% 3 7% 5% 5% 4 3 5% 6% 33%	2725
November	1st to 10th	Night	14% 9% 3 7% 5% 4 4 3 5% 7% 39%	2666
	11th to 20th	Night	18% 14% 4 9% 5% 4 3 3 5% 6% 30%	2730
	21st to end	Night	22% 16% 4 8% 4 4 4 2 5% 6% 24%	2900
December	1st to 10th	Night	16% 18% 8% 15% 6% 4 4 3 4 4 18%	4720
	11th to 20th	Night	18% 16% 7% 14% 6% 4 4 3 4 4 19%	5345
	21st to end	Night	26% 20% 6% 11% 5% 4 4 3 4 5% 14%	7080

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	65% 7% 10% 12% 5% 1	4692
	11th to 20th	Day	71% 4 7% 7% 10%	5165
	21st to end	Day	66% 5% 11% 13% 6%	5780
February	1st to 10th	Day	59% 6% 10% 17% 7% 1	1890
	11th to 20th	Day	59% 5% 12% 16% 8% 1	1957
	21st to end	Day	55% 6% 13% 17% 7% 2	1730
March	1st to 10th	Day	53% 4 12% 21% 10%	4805
	11th to 20th	Day	44% 6% 15% 24% 10% 1	5090
	21st to end	Day	50% 5% 15% 18% 11% 1	5586
April	1st to 10th	Day	46% 7% 14% 19% 14% 1	2364
	11th to 20th	Day	46% 6% 12% 21% 13% 2	2702
	21st to end	Day	45% 6% 13% 23% 11% 3	2730
May	1st to 10th	Day	47% 6% 12% 21% 12% 2	7651
	11th to 20th	Day	43% 8% 15% 21% 11% 2	7630
	21st to end	Day	39% 6% 11% 20% 18% 6%	8405
June	1st to 10th	Day	36% 7% 12% 28% 14% 2	2915
	11th to 20th	Day	34% 9% 16% 23% 16% 2	3076
	21st to end	Day	31% 9% 16% 24% 17% 3	2908
July	1st to 10th	Day	33% 6% 12% 30% 18% 2	6291
	11th to 20th	Day	29% 6% 15% 30% 18% 2	6061
	21st to end	Day	34% 6% 15% 22% 20% 3	6240
August	1st to 10th	Day	33% 7% 16% 29% 15% 1	4221
	11th to 20th	Day	35% 8% 13% 34% 9% 1	4213
	21st to end	Day	33% 7% 16% 30% 13% 1	4674
September	1st to 10th	Day	33% 7% 19% 24% 17% 1	2241
	11th to 20th	Day	30% 8% 14% 31% 17% 1	2200
	21st to end	Day	42% 8% 12% 22% 15% 1	2200
October	1st to 10th	Day	29% 6% 14% 32% 18% 1	3433
	11th to 20th	Day	39% 6% 13% 25% 17%	3240
	21st to end	Day	43% 6% 14% 23% 14%	3386
November	1st to 10th	Day	45% 8% 11% 22% 13% 1	1852
	11th to 20th	Day	55% 5% 13% 16% 10% 1	1890
	21st to end	Day	60% 7% 13% 16% 5%	1716
December	1st to 10th	Day	69% 7% 11% 9% 4	2680
	11th to 20th	Day	68% 6% 11% 12% 3	3066
	21st to end	Day	75% 6% 8% 8% 4	4100
January	1st to 10th	Night	65% 6% 9% 14% 7%	8233
	11th to 20th	Night	68% 4 9% 10% 8% 1	7767
	21st to end	Night	59% 5% 11% 16% 9%	8401
February	1st to 10th	Night	61% 6% 11% 16% 5% 1	2730
	11th to 20th	Night	59% 6% 10% 17% 8% 1	2556
	21st to end	Night	58% 5% 11% 17% 8% 1	2076
March	1st to 10th	Night	50% 5% 14% 20% 11% 1	5266
	11th to 20th	Night	38% 6% 16% 25% 14% 1	5090
	21st to end	Night	48% 5% 11% 19% 15% 1	5588
April	1st to 10th	Night	50% 6% 10% 18% 13% 2	2273
	11th to 20th	Night	46% 6% 11% 18% 16% 3	1867
	21st to end	Night	45% 5% 9% 21% 15% 4	1890
May	1st to 10th	Night	55% 6% 9% 13% 14% 3	5264
	11th to 20th	Night	45% 6% 11% 23% 13% 2	5235
	21st to end	Night	41% 6% 11% 21% 19% 3	5771
June	1st to 10th	Night	36% 8% 9% 24% 19% 4	1693
	11th to 20th	Night	36% 7% 14% 24% 16% 3	1435
	21st to end	Night	34% 7% 11% 24% 21% 1	1484
July	1st to 10th	Night	31% 6% 15% 26% 17% 5%	3580
	11th to 20th	Night	34% 7% 13% 27% 18% 2	3782
	21st to end	Night	31% 6% 14% 21% 25% 2	4297
August	1st to 10th	Night	38% 6% 12% 27% 15% 2	2904
	11th to 20th	Night	35% 7% 9% 34% 13% 2	2902
	21st to end	Night	33% 7% 12% 30% 16% 1	3223
September	1st to 10th	Night	34% 7% 13% 28% 15% 3	2135
	11th to 20th	Night	30% 7% 11% 29% 21% 2	2200
	21st to end	Night	44% 7% 10% 21% 17% 1	2200
October	1st to 10th	Night	28% 5% 9% 30% 27% 1	3746
	11th to 20th	Night	44% 5% 10% 23% 18%	3899
	21st to end	Night	41% 4 11% 27% 14% 1	4399
November	1st to 10th	Night	45% 6% 11% 21% 15% 1	2666
	11th to 20th	Night	56% 6% 11% 16% 10% 1	2730
	21st to end	Night	62% 6% 12% 16% 4	2900
December	1st to 10th	Night	70% 5% 10% 11% 3	4720
	11th to 20th	Night	68% 5% 13% 10% 4	5348
	21st to end	Night	74% 5% 9% 9% 3	7080

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% 11% 31% 29% 8% 1	330
	11th to 20th	Day	22% 12% 37% 24% 5% 1	330
	21st to end	Day	25% 7% 29% 31% 8% 1	363
February	1st to 10th	Day	21% 8% 28% 34% 8% 1	330
	11th to 20th	Day	19% 8% 33% 31% 9%	330
	21st to end	Day	17% 8% 38% 33% 5%	273
March	1st to 10th	Day	19% 7% 28% 36% 10%	425
	11th to 20th	Day	16% 7% 32% 34% 10% 1	540
	21st to end	Day	20% 7% 27% 37% 8% 1	594
April	1st to 10th	Day	15% 7% 26% 38% 13% 1	540
	11th to 20th	Day	17% 6% 26% 34% 13% 5%	532
	21st to end	Day	17% 3 24% 37% 18% 1	540
May	1st to 10th	Day	22% 4 18% 36% 18% 3	543
	11th to 20th	Day	16% 4 17% 33% 27% 5%	567
	21st to end	Day	13% 1 12% 34% 31% 9%	617
June	1st to 10th	Day	11% 3 14% 35% 32% 5%	598
	11th to 20th	Day	10% 3 14% 37% 30% 6%	756
	21st to end	Day	11% 2 11% 35% 34% 6%	730
July	1st to 10th	Day	8% 2 9% 33% 33% 15%	721
	11th to 20th	Day	10% 3 8% 30% 39% 10%	624
	21st to end	Day	9% 2 7% 29% 43% 10%	576
August	1st to 10th	Day	8% 2 9% 29% 38% 13%	526
	11th to 20th	Day	10% 2 9% 27% 39% 13%	519
	21st to end	Day	8% 2 8% 30% 40% 11%	583
September	1st to 10th	Day	11% 2 14% 27% 30% 16%	530
	11th to 20th	Day	10% 2 9% 22% 40% 18%	530
	21st to end	Day	20% 5% 15% 22% 28% 10%	530
October	1st to 10th	Day	12% 2 20% 26% 27% 13%	530
	11th to 20th	Day	17% 9% 23% 31% 17% 4	530
	21st to end	Day	23% 9% 26% 28% 13% 2	493
November	1st to 10th	Day	16% 8% 25% 29% 18% 4	330
	11th to 20th	Day	22% 13% 26% 25% 12% 2	330
	21st to end	Day	23% 9% 36% 28% 4	238
December	1st to 10th	Day	20% 13% 31% 27% 9%	220
	11th to 20th	Day	27% 14% 35% 20% 5%	220
	21st to end	Day	27% 11% 30% 27% 6%	322
January	1st to 10th	Night	24% 10% 34% 24% 7% 1	1050
	11th to 20th	Night	25% 11% 36% 23% 6%	875
	21st to end	Night	22% 8% 33% 30% 6%	924
February	1st to 10th	Night	24% 6% 31% 32% 6%	840
	11th to 20th	Night	23% 7% 31% 33% 6%	823
	21st to end	Night	24% 8% 36% 29% 4	692
March	1st to 10th	Night	20% 7% 31% 33% 8% 1	840
	11th to 20th	Night	18% 7% 33% 32% 9% 2	840
	21st to end	Night	21% 6% 28% 32% 11% 2	924
April	1st to 10th	Night	20% 8% 28% 34% 9% 1	803
	11th to 20th	Night	18% 5% 27% 33% 14% 2	623
	21st to end	Night	18% 5% 23% 38% 14% 2	630
May	1st to 10th	Night	19% 4 24% 33% 17% 3	630
	11th to 20th	Night	19% 4 17% 33% 23% 4	621
	21st to end	Night	11% 3 16% 31% 31% 8%	683
June	1st to 10th	Night	13% 2 18% 36% 28% 3	467
	11th to 20th	Night	10% 1 15% 38% 32% 3	410
	21st to end	Night	9% 3 15% 38% 31% 5%	484
July	1st to 10th	Night	10% 2 10% 32% 38% 9%	585
	11th to 20th	Night	10% 3 11% 34% 33% 8%	582
	21st to end	Night	8% 2 11% 37% 37% 6%	657
August	1st to 10th	Night	9% 2 12% 36% 33% 10%	597
	11th to 20th	Night	8% 3 13% 32% 34% 10%	594
	21st to end	Night	10% 1 11% 35% 34% 9%	660
September	1st to 10th	Night	12% 3 15% 27% 33% 10%	768
	11th to 20th	Night	10% 3 11% 28% 36% 12%	800
	21st to end	Night	18% 5% 16% 29% 24% 8%	800
October	1st to 10th	Night	16% 4 23% 26% 24% 7%	800
	11th to 20th	Night	22% 11% 27% 23% 15% 3	800
	21st to end	Night	25% 11% 28% 27% 8%	880
November	1st to 10th	Night	18% 10% 28% 28% 14% 2	820
	11th to 20th	Night	24% 14% 33% 20% 8% 2	840
	21st to end	Night	30% 12% 29% 21% 7%	840
December	1st to 10th	Night	28% 15% 30% 21% 6%	840
	11th to 20th	Night	25% 13% 36% 21% 5%	840
	21st to end	Night	29% 10% 32% 24% 4	1050

Page generated at 2026-06-13 02:31:44. Version ac07

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