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 2025-02-21.

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%	108670
	Night	15% 11% 4 9% 5% 5% 4 3 5% 6% 32%	109923
Transparency	Day	46% 7% 13% 21% 12% 1	112311
	Night	51% 6% 11% 19% 12% 1	114421
Seeing	Day	15% 5% 19% 31% 23% 6%	15502
	Night	19% 7% 25% 29% 17% 3	25227

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% 17% 6% 16% 5% 5% 4 3 5% 5% 21%	3617
	11th to 20th	Day	14% 17% 6% 15% 9% 9% 4 3 4 4 15%	3971
	21st to end	Day	21% 15% 5% 12% 6% 5% 5% 4 5% 5% 16%	4466
February	1st to 10th	Day	15% 15% 5% 11% 7% 5% 4 3 5% 6% 25%	1800
	11th to 20th	Day	14% 12% 4 13% 7% 5% 5% 4 5% 6% 25%	1853
	21st to end	Day	16% 11% 4 9% 6% 4 6% 4 6% 6% 28%	1570
March	1st to 10th	Day	19% 11% 4 9% 5% 5% 4 3 5% 6% 29%	3270
	11th to 20th	Day	12% 10% 3 8% 6% 5% 4 4 5% 6% 35%	3480
	21st to end	Day	17% 9% 3 8% 5% 4 5% 4 6% 6% 33%	3815
April	1st to 10th	Day	12% 9% 3 7% 6% 5% 5% 5% 6% 7% 35%	2138
	11th to 20th	Day	16% 7% 3 7% 5% 5% 5% 4 6% 7% 36%	2442
	21st to end	Day	17% 7% 2 8% 5% 4 5% 4 5% 7% 37%	2470
May	1st to 10th	Day	16% 8% 3 8% 5% 4 5% 4 6% 7% 34%	4082
	11th to 20th	Day	15% 8% 3 7% 5% 5% 5% 5% 6% 9% 32%	4081
	21st to end	Day	8% 5% 2 7% 5% 4 4 4 7% 8% 47%	4476
June	1st to 10th	Day	10% 6% 2 7% 5% 4 5% 4 7% 9% 42%	2637
	11th to 20th	Day	7% 6% 2 6% 4 4 5% 5% 7% 10% 44%	2850
	21st to end	Day	8% 5% 2 5% 5% 4 4 5% 8% 11% 43%	2763
July	1st to 10th	Day	9% 5% 3 6% 4 4 5% 4 6% 9% 45%	4440
	11th to 20th	Day	7% 4 2 4 4 4 4 4 7% 9% 51%	4286
	21st to end	Day	7% 5% 2 6% 5% 4 5% 5% 7% 8% 46%	4466
August	1st to 10th	Day	12% 5% 2 6% 3 3 4 3 7% 9% 46%	4104
	11th to 20th	Day	9% 5% 2 6% 5% 5% 5% 5% 7% 9% 41%	4044
	21st to end	Day	8% 5% 2 6% 4 5% 5% 4 7% 10% 44%	4532
September	1st to 10th	Day	11% 6% 2 5% 4 3 4 4 6% 8% 48%	2130
	11th to 20th	Day	8% 6% 2 5% 4 4 5% 4 6% 8% 48%	2090
	21st to end	Day	18% 7% 3 5% 4 4 4 4 6% 6% 40%	2090
October	1st to 10th	Day	12% 6% 2 7% 6% 4 4 3 6% 7% 43%	2003
	11th to 20th	Day	18% 8% 3 7% 4 3 5% 3 6% 8% 35%	1900
	21st to end	Day	20% 9% 3 7% 5% 4 6% 4 5% 8% 30%	2005
November	1st to 10th	Day	11% 10% 3 7% 4 5% 4 4 6% 7% 38%	1762
	11th to 20th	Day	16% 14% 4 8% 5% 4 4 3 5% 7% 30%	1800
	21st to end	Day	18% 16% 6% 8% 4 4 4 4 5% 6% 24%	1635
December	1st to 10th	Day	16% 14% 10% 15% 7% 5% 4 3 5% 4 17%	2600
	11th to 20th	Day	21% 18% 6% 10% 7% 4 4 4 4 6% 17%	2990
	21st to end	Day	24% 18% 6% 12% 6% 5% 4 3 4 4 13%	4012
January	1st to 10th	Night	14% 17% 7% 13% 6% 4 4 3 4 5% 24%	6348
	11th to 20th	Night	13% 19% 8% 13% 6% 9% 5% 3 4 4 15%	5973
	21st to end	Night	21% 16% 7% 10% 4 4 3 3 4 5% 24%	6490
February	1st to 10th	Night	17% 14% 5% 10% 7% 6% 5% 4 5% 6% 23%	2600
	11th to 20th	Night	16% 13% 4 10% 6% 5% 5% 4 6% 6% 25%	2429
	21st to end	Night	20% 12% 4 9% 6% 4 4 3 5% 6% 28%	1885
March	1st to 10th	Night	19% 11% 4 8% 4 4 4 3 4 5% 35%	3581
	11th to 20th	Night	11% 7% 2 7% 5% 5% 6% 4 6% 8% 40%	3480
	21st to end	Night	16% 9% 4 8% 4 4 4 3 5% 6% 36%	3817
April	1st to 10th	Night	15% 11% 4 8% 5% 4 5% 3 5% 6% 35%	2057
	11th to 20th	Night	17% 7% 2 7% 4 4 5% 3 6% 8% 36%	1687
	21st to end	Night	16% 8% 3 6% 5% 5% 4 4 6% 6% 38%	1710
May	1st to 10th	Night	17% 8% 3 8% 5% 5% 6% 4 5% 7% 31%	2813
	11th to 20th	Night	14% 8% 3 7% 5% 4 5% 4 6% 8% 34%	2812
	21st to end	Night	10% 4 2 6% 4 4 4 4 6% 9% 48%	3079
June	1st to 10th	Night	12% 5% 1 6% 4 4 5% 5% 7% 8% 43%	1533
	11th to 20th	Night	9% 5% 3 5% 6% 5% 5% 4 7% 8% 44%	1330
	21st to end	Night	9% 5% 2 5% 6% 4 4 4 7% 9% 45%	1410
July	1st to 10th	Night	9% 4 1 5% 4 3 4 4 6% 11% 49%	2530
	11th to 20th	Night	9% 4 2 5% 4 3 5% 3 7% 9% 50%	2675
	21st to end	Night	5% 4 2 6% 4 4 5% 5% 7% 10% 47%	3087
August	1st to 10th	Night	15% 6% 2 6% 4 4 4 3 5% 8% 44%	2825
	11th to 20th	Night	9% 5% 2 6% 5% 4 5% 3 6% 7% 48%	2785
	21st to end	Night	7% 4 2 6% 5% 5% 5% 5% 7% 7% 47%	3124
September	1st to 10th	Night	10% 5% 2 6% 5% 4 4 4 5% 7% 48%	2027
	11th to 20th	Night	9% 5% 2 6% 4 4 4 3 5% 7% 52%	2090
	21st to end	Night	16% 7% 2 7% 5% 5% 4 3 5% 6% 40%	2090
October	1st to 10th	Night	14% 6% 2 6% 4 4 5% 3 4 7% 44%	2176
	11th to 20th	Night	19% 9% 3 7% 5% 5% 3 4 5% 6% 34%	2280
	21st to end	Night	22% 9% 3 7% 5% 5% 5% 3 5% 6% 32%	2589
November	1st to 10th	Night	14% 9% 3 7% 5% 4 4 3 5% 7% 39%	2536
	11th to 20th	Night	18% 14% 4 9% 5% 4 3 3 5% 5% 29%	2600
	21st to end	Night	22% 16% 4 8% 4 4 4 2 5% 6% 24%	2762
December	1st to 10th	Night	15% 18% 8% 15% 6% 4 4 3 4 4 18%	4580
	11th to 20th	Night	18% 17% 7% 14% 6% 4 4 3 4 4 19%	5205
	21st to end	Night	26% 20% 6% 11% 5% 4 4 3 4 5% 14%	6928

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	64% 7% 10% 12% 6% 1	3618
	11th to 20th	Day	74% 5% 8% 6% 7%	3971
	21st to end	Day	69% 5% 11% 10% 5%	4466
February	1st to 10th	Day	60% 7% 10% 16% 7% 1	1800
	11th to 20th	Day	59% 5% 11% 16% 7% 1	1862
	21st to end	Day	54% 6% 13% 17% 7% 2	1570
March	1st to 10th	Day	55% 6% 11% 23% 5%	3270
	11th to 20th	Day	46% 7% 15% 21% 9% 1	3480
	21st to end	Day	49% 6% 16% 18% 10% 1	3815
April	1st to 10th	Day	45% 7% 14% 19% 14% 1	2138
	11th to 20th	Day	46% 6% 13% 20% 13% 2	2442
	21st to end	Day	46% 6% 13% 21% 11% 3	2470
May	1st to 10th	Day	45% 8% 11% 23% 11% 2	4120
	11th to 20th	Day	44% 11% 16% 20% 9% 1	4085
	21st to end	Day	31% 10% 13% 21% 17% 8%	4489
June	1st to 10th	Day	37% 7% 13% 28% 13% 2	2637
	11th to 20th	Day	33% 9% 17% 23% 16% 2	2850
	21st to end	Day	32% 9% 15% 24% 17% 3	2763
July	1st to 10th	Day	36% 6% 12% 25% 19% 2	4371
	11th to 20th	Day	26% 6% 14% 33% 19% 1	4211
	21st to end	Day	33% 7% 17% 19% 20% 3	4324
August	1st to 10th	Day	34% 7% 15% 29% 15% 1	4091
	11th to 20th	Day	35% 8% 13% 34% 10% 1	4083
	21st to end	Day	33% 7% 16% 29% 14% 1	4531
September	1st to 10th	Day	33% 7% 19% 23% 16% 1	2130
	11th to 20th	Day	31% 8% 13% 29% 17% 1	2090
	21st to end	Day	42% 8% 12% 22% 15%	2090
October	1st to 10th	Day	29% 7% 14% 31% 18% 1	3328
	11th to 20th	Day	39% 6% 13% 24% 17% 1	3140
	21st to end	Day	43% 6% 14% 23% 13%	3281
November	1st to 10th	Day	44% 8% 12% 22% 13% 1	1762
	11th to 20th	Day	55% 5% 13% 16% 10% 1	1800
	21st to end	Day	59% 7% 13% 15% 5%	1635
December	1st to 10th	Day	69% 7% 11% 9% 4	2600
	11th to 20th	Day	69% 6% 10% 12% 3	2986
	21st to end	Day	75% 6% 8% 8% 3	4012
January	1st to 10th	Night	63% 6% 8% 15% 7% 1	6348
	11th to 20th	Night	73% 4 8% 9% 5% 1	5973
	21st to end	Night	64% 5% 11% 10% 9%	6490
February	1st to 10th	Night	62% 6% 11% 15% 5% 1	2600
	11th to 20th	Night	59% 6% 10% 17% 8% 1	2431
	21st to end	Night	57% 5% 11% 18% 8% 1	1885
March	1st to 10th	Night	51% 5% 13% 22% 9%	3581
	11th to 20th	Night	39% 8% 19% 18% 15% 1	3480
	21st to end	Night	47% 6% 12% 22% 12% 1	3817
April	1st to 10th	Night	49% 6% 10% 19% 14% 2	2057
	11th to 20th	Night	45% 6% 11% 18% 16% 3	1687
	21st to end	Night	46% 5% 9% 20% 16% 4	1710
May	1st to 10th	Night	50% 7% 9% 17% 14% 3	2840
	11th to 20th	Night	45% 8% 12% 22% 12% 2	2813
	21st to end	Night	31% 8% 12% 23% 20% 5%	3087
June	1st to 10th	Night	36% 8% 10% 26% 16% 4	1533
	11th to 20th	Night	36% 7% 14% 23% 16% 3	1330
	21st to end	Night	35% 7% 11% 25% 21% 1	1410
July	1st to 10th	Night	29% 5% 13% 28% 18% 6%	2490
	11th to 20th	Night	29% 7% 14% 29% 20% 2	2627
	21st to end	Night	30% 8% 17% 21% 22% 2	2988
August	1st to 10th	Night	39% 6% 12% 27% 14% 2	2814
	11th to 20th	Night	35% 8% 9% 34% 13% 2	2812
	21st to end	Night	34% 7% 12% 29% 17% 1	3124
September	1st to 10th	Night	34% 7% 13% 26% 16% 3	2027
	11th to 20th	Night	32% 7% 11% 27% 21% 2	2090
	21st to end	Night	44% 7% 10% 21% 16% 1	2090
October	1st to 10th	Night	28% 5% 9% 29% 27% 1	3631
	11th to 20th	Night	44% 5% 10% 23% 17%	3779
	21st to end	Night	41% 4 11% 28% 14% 1	4263
November	1st to 10th	Night	45% 7% 11% 21% 15% 1	2536
	11th to 20th	Night	57% 6% 11% 16% 9% 1	2600
	21st to end	Night	62% 6% 12% 16% 4	2762
December	1st to 10th	Night	71% 5% 10% 11% 3	4580
	11th to 20th	Night	68% 5% 13% 10% 3	5208
	21st to end	Night	74% 5% 10% 9% 3	6928

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	21% 10% 30% 29% 8% 1	300
	11th to 20th	Day	22% 10% 37% 25% 5% 1	300
	21st to end	Day	26% 6% 29% 29% 8% 1	330
February	1st to 10th	Day	22% 8% 29% 33% 6% 1	300
	11th to 20th	Day	20% 7% 34% 30% 8%	300
	21st to end	Day	20% 8% 38% 30% 4	225
March	1st to 10th	Day	20% 7% 26% 35% 11%	355
	11th to 20th	Day	16% 7% 30% 34% 11% 1	460
	21st to end	Day	22% 7% 27% 36% 8% 1	506
April	1st to 10th	Day	12% 7% 26% 40% 14% 1	460
	11th to 20th	Day	20% 6% 25% 33% 12% 5%	452
	21st to end	Day	18% 3 25% 36% 16% 2	460
May	1st to 10th	Day	22% 3 19% 33% 20% 3	463
	11th to 20th	Day	16% 3 16% 30% 28% 6%	487
	21st to end	Day	11% 1 10% 33% 34% 11%	529
June	1st to 10th	Day	11% 3 14% 36% 31% 5%	515
	11th to 20th	Day	9% 3 14% 36% 31% 7%	680
	21st to end	Day	12% 2 12% 36% 32% 6%	680
July	1st to 10th	Day	7% 2 10% 32% 33% 15%	671
	11th to 20th	Day	11% 3 7% 31% 39% 10%	579
	21st to end	Day	9% 2 7% 29% 43% 10%	532
August	1st to 10th	Day	9% 3 10% 30% 36% 13%	486
	11th to 20th	Day	10% 2 9% 28% 39% 12%	479
	21st to end	Day	8% 2 9% 29% 40% 12%	539
September	1st to 10th	Day	12% 2 13% 28% 31% 15%	490
	11th to 20th	Day	10% 2 9% 23% 38% 18%	490
	21st to end	Day	21% 5% 16% 23% 27% 9%	490
October	1st to 10th	Day	13% 2 21% 25% 27% 13%	490
	11th to 20th	Day	17% 9% 23% 30% 17% 4	490
	21st to end	Day	23% 9% 26% 27% 13% 2	454
November	1st to 10th	Day	14% 8% 25% 29% 20% 4	300
	11th to 20th	Day	22% 13% 26% 25% 12% 2	300
	21st to end	Day	24% 8% 35% 29% 3	217
December	1st to 10th	Day	19% 14% 30% 28% 10%	200
	11th to 20th	Day	28% 13% 34% 22% 4	200
	21st to end	Day	26% 10% 31% 27% 6%	293
January	1st to 10th	Night	24% 10% 35% 23% 7% 1	1000
	11th to 20th	Night	26% 10% 34% 23% 6%	834
	21st to end	Night	23% 8% 32% 30% 6%	880
February	1st to 10th	Night	25% 6% 32% 31% 5% 1	800
	11th to 20th	Night	23% 8% 30% 33% 6%	783
	21st to end	Night	25% 7% 36% 29% 4	629
March	1st to 10th	Night	20% 7% 29% 34% 9% 1	760
	11th to 20th	Night	18% 6% 33% 32% 9% 2	760
	21st to end	Night	21% 6% 27% 32% 12% 2	836
April	1st to 10th	Night	19% 7% 29% 34% 10% 1	727
	11th to 20th	Night	19% 5% 27% 33% 13% 2	563
	21st to end	Night	18% 5% 24% 37% 14% 2	570
May	1st to 10th	Night	18% 4 23% 34% 18% 3	570
	11th to 20th	Night	20% 4 16% 32% 24% 4	561
	21st to end	Night	9% 2 16% 30% 34% 9%	617
June	1st to 10th	Night	13% 1 20% 35% 27% 3	423
	11th to 20th	Night	10% 2 15% 37% 33% 3	380
	21st to end	Night	9% 3 15% 38% 30% 5%	460
July	1st to 10th	Night	10% 2 11% 33% 37% 9%	555
	11th to 20th	Night	10% 4 11% 34% 33% 9%	552
	21st to end	Night	7% 2 11% 37% 37% 5%	624
August	1st to 10th	Night	9% 2 12% 37% 31% 10%	567
	11th to 20th	Night	8% 3 13% 33% 33% 10%	564
	21st to end	Night	10% 1 11% 34% 34% 9%	627
September	1st to 10th	Night	12% 3 14% 28% 33% 9%	729
	11th to 20th	Night	10% 3 12% 30% 35% 10%	760
	21st to end	Night	19% 5% 16% 29% 24% 7%	760
October	1st to 10th	Night	17% 4 23% 26% 23% 7%	760
	11th to 20th	Night	22% 11% 26% 23% 14% 3	760
	21st to end	Night	26% 11% 28% 27% 8%	836
November	1st to 10th	Night	19% 10% 27% 28% 14% 2	780
	11th to 20th	Night	25% 13% 33% 20% 8% 2	800
	21st to end	Night	30% 13% 29% 21% 8%	800
December	1st to 10th	Night	28% 15% 30% 21% 6% 1	800
	11th to 20th	Night	25% 12% 36% 21% 6%	800
	21st to end	Night	30% 10% 32% 24% 5%	1000

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