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 2024-01-31.

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% 8% 4 6% 6% 3 5% 5% 6% 8% 36%	74977
	Night	16% 10% 4 7% 6% 3 5% 4 5% 7% 33%	75126
Transparency	Day	45% 8% 13% 21% 12% 1	74688
	Night	51% 7% 11% 19% 11% 1	74935
Seeing	Day	16% 5% 19% 30% 23% 6%	14101
	Night	20% 7% 25% 29% 17% 3	23833

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	17% 16% 4 9% 9% 5% 6% 4 5% 6% 20%	1517
	11th to 20th	Day	18% 14% 6% 11% 10% 5% 5% 4 4 7% 16%	1671
	21st to end	Day	18% 16% 6% 10% 7% 4 4 5% 5% 5% 19%	1872
February	1st to 10th	Day	16% 14% 6% 9% 9% 4 4 4 5% 6% 24%	1620
	11th to 20th	Day	15% 10% 5% 11% 9% 4 6% 5% 5% 6% 24%	1662
	21st to end	Day	17% 10% 5% 8% 7% 3 5% 5% 5% 7% 28%	1480
March	1st to 10th	Day	16% 9% 5% 8% 6% 3 4 5% 6% 7% 30%	1880
	11th to 20th	Day	13% 10% 4 7% 7% 3 5% 5% 5% 7% 34%	1980
	21st to end	Day	19% 10% 4 8% 6% 3 5% 4 5% 7% 30%	2178
April	1st to 10th	Day	13% 7% 4 6% 7% 3 6% 6% 6% 7% 36%	2025
	11th to 20th	Day	16% 7% 3 6% 6% 4 6% 5% 6% 7% 36%	2312
	21st to end	Day	18% 7% 3 6% 5% 3 5% 4 5% 7% 37%	2340
May	1st to 10th	Day	16% 7% 2 6% 6% 3 5% 5% 6% 8% 36%	2340
	11th to 20th	Day	16% 7% 2 6% 5% 4 5% 6% 6% 7% 36%	2301
	21st to end	Day	9% 4 2 5% 6% 3 4 6% 7% 8% 45%	2531
June	1st to 10th	Day	10% 6% 2 6% 5% 3 5% 5% 6% 9% 43%	2497
	11th to 20th	Day	8% 6% 3 5% 5% 3 5% 6% 6% 9% 44%	2700
	21st to end	Day	8% 4 2 4 6% 2 5% 6% 7% 11% 44%	2618
July	1st to 10th	Day	7% 4 2 4 4 3 5% 5% 6% 10% 50%	2520
	11th to 20th	Day	8% 4 2 4 4 2 4 5% 7% 10% 49%	2436
	21st to end	Day	7% 5% 2 5% 5% 3 5% 5% 5% 10% 48%	2547
August	1st to 10th	Day	7% 4 2 5% 4 2 5% 5% 7% 10% 48%	2327
	11th to 20th	Day	8% 5% 2 5% 6% 3 5% 7% 7% 10% 42%	2303
	21st to end	Day	8% 4 3 4 4 3 5% 5% 6% 9% 48%	2574
September	1st to 10th	Day	11% 6% 3 4 4 2 4 5% 6% 8% 46%	2019
	11th to 20th	Day	9% 5% 3 5% 4 3 5% 6% 6% 8% 47%	1980
	21st to end	Day	17% 6% 3 4 4 3 5% 5% 6% 7% 42%	1980
October	1st to 10th	Day	13% 6% 3 6% 7% 3 4 4 6% 6% 42%	1898
	11th to 20th	Day	19% 8% 4 6% 5% 3 4 5% 6% 8% 33%	1800
	21st to end	Day	21% 9% 3 6% 5% 3 5% 6% 5% 7% 29%	1900
November	1st to 10th	Day	11% 9% 4 5% 6% 3 5% 5% 6% 7% 38%	1672
	11th to 20th	Day	16% 13% 5% 7% 6% 3 4 4 4 7% 30%	1710
	21st to end	Day	19% 14% 6% 7% 5% 3 5% 5% 5% 7% 25%	1554
December	1st to 10th	Day	18% 15% 9% 11% 8% 4 5% 5% 5% 4 17%	1520
	11th to 20th	Day	17% 14% 7% 9% 7% 4 5% 5% 5% 7% 21%	1910
	21st to end	Day	25% 17% 8% 10% 8% 3 4 4 4 5% 11%	2803
January	1st to 10th	Night	18% 14% 6% 9% 8% 4 4 4 4 5% 24%	2648
	11th to 20th	Night	20% 16% 7% 10% 6% 4 5% 4 4 4 18%	2503
	21st to end	Night	17% 15% 8% 10% 6% 4 4 4 4 5% 22%	2711
February	1st to 10th	Night	18% 13% 6% 9% 8% 4 5% 5% 4 6% 23%	2340
	11th to 20th	Night	17% 12% 5% 9% 6% 3 5% 5% 5% 6% 25%	2180
	21st to end	Night	21% 11% 5% 8% 6% 3 4 4 5% 5% 29%	1776
March	1st to 10th	Night	16% 9% 4 8% 6% 3 5% 5% 5% 6% 33%	2078
	11th to 20th	Night	14% 8% 2 5% 5% 4 6% 5% 5% 8% 38%	1980
	21st to end	Night	19% 9% 4 7% 5% 3 4 4 5% 6% 34%	2178
April	1st to 10th	Night	15% 9% 4 7% 6% 3 4 5% 5% 6% 36%	1949
	11th to 20th	Night	17% 6% 3 6% 5% 3 5% 5% 6% 8% 36%	1597
	21st to end	Night	16% 7% 3 5% 5% 3 4 5% 6% 6% 39%	1620
May	1st to 10th	Night	16% 8% 3 7% 7% 4 6% 6% 5% 8% 30%	1620
	11th to 20th	Night	16% 8% 3 5% 6% 3 5% 4 5% 7% 38%	1592
	21st to end	Night	9% 4 2 5% 5% 3 5% 5% 6% 10% 46%	1744
June	1st to 10th	Night	12% 5% 2 6% 4 3 5% 6% 7% 8% 43%	1453
	11th to 20th	Night	10% 5% 3 5% 6% 3 5% 5% 6% 9% 44%	1260
	21st to end	Night	9% 5% 2 4 6% 3 4 4 7% 9% 46%	1335
July	1st to 10th	Night	8% 4 2 5% 5% 3 4 5% 6% 9% 51%	1440
	11th to 20th	Night	9% 4 2 4 4 3 5% 5% 7% 9% 48%	1520
	21st to end	Night	6% 4 2 5% 5% 2 5% 6% 7% 9% 50%	1771
August	1st to 10th	Night	7% 4 2 5% 5% 3 6% 5% 5% 9% 50%	1611
	11th to 20th	Night	8% 4 2 5% 6% 3 5% 6% 7% 8% 46%	1598
	21st to end	Night	8% 3 3 5% 4 4 4 6% 6% 8% 49%	1782
September	1st to 10th	Night	11% 5% 2 5% 6% 3 5% 5% 5% 7% 47%	1919
	11th to 20th	Night	9% 4 2 5% 5% 2 5% 4 5% 7% 50%	1980
	21st to end	Night	15% 6% 2 5% 5% 4 4 5% 5% 7% 42%	1980
October	1st to 10th	Night	15% 6% 2 6% 5% 3 5% 5% 4 8% 43%	2061
	11th to 20th	Night	20% 9% 3 6% 6% 4 4 4 5% 7% 33%	2160
	21st to end	Night	23% 9% 3 6% 6% 4 4 4 4 5% 31%	2452
November	1st to 10th	Night	14% 9% 3 7% 6% 2 4 4 5% 7% 39%	2406
	11th to 20th	Night	19% 13% 5% 8% 6% 3 3 4 5% 6% 29%	2470
	21st to end	Night	22% 15% 5% 7% 5% 3 4 3 5% 6% 26%	2623
December	1st to 10th	Night	20% 17% 6% 11% 7% 4 5% 4 4 5% 17%	2660
	11th to 20th	Night	18% 15% 5% 10% 6% 3 5% 4 5% 5% 23%	3285
	21st to end	Night	28% 21% 7% 9% 6% 3 3 3 3 5% 11%	4844

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% 11% 11% 5% 1	1518
	11th to 20th	Day	69% 8% 12% 9% 2	1671
	21st to end	Day	65% 7% 11% 11% 5%	1872
February	1st to 10th	Day	61% 6% 10% 15% 7%	1620
	11th to 20th	Day	60% 6% 11% 16% 7% 1	1671
	21st to end	Day	55% 6% 12% 17% 8% 2	1480
March	1st to 10th	Day	52% 7% 13% 20% 8% 1	1880
	11th to 20th	Day	48% 7% 11% 19% 12% 2	1980
	21st to end	Day	54% 6% 11% 21% 7% 1	2178
April	1st to 10th	Day	45% 7% 14% 19% 14% 1	2025
	11th to 20th	Day	47% 6% 12% 19% 13% 2	2312
	21st to end	Day	46% 6% 13% 21% 11% 3	2340
May	1st to 10th	Day	45% 8% 11% 23% 12% 2	2340
	11th to 20th	Day	44% 9% 13% 17% 15% 2	2305
	21st to end	Day	33% 9% 15% 26% 15% 2	2531
June	1st to 10th	Day	37% 7% 13% 28% 13% 2	2497
	11th to 20th	Day	34% 9% 17% 22% 16% 2	2700
	21st to end	Day	31% 10% 15% 25% 17% 3	2618
July	1st to 10th	Day	31% 8% 11% 28% 19% 3	2451
	11th to 20th	Day	29% 7% 15% 29% 18% 2	2361
	21st to end	Day	32% 8% 15% 25% 18% 3	2405
August	1st to 10th	Day	29% 8% 16% 32% 14%	2314
	11th to 20th	Day	33% 10% 16% 27% 12% 2	2303
	21st to end	Day	31% 8% 16% 25% 18% 2	2574
September	1st to 10th	Day	34% 7% 20% 22% 16% 2	2019
	11th to 20th	Day	32% 9% 14% 29% 15% 1	1980
	21st to end	Day	40% 8% 12% 23% 16% 1	1980
October	1st to 10th	Day	41% 8% 11% 23% 15% 1	1898
	11th to 20th	Day	48% 8% 14% 19% 10% 1	1800
	21st to end	Day	54% 8% 13% 16% 8% 1	1900
November	1st to 10th	Day	44% 8% 12% 21% 13% 1	1672
	11th to 20th	Day	55% 5% 14% 16% 10% 1	1710
	21st to end	Day	58% 7% 14% 16% 5%	1554
December	1st to 10th	Day	68% 8% 10% 10% 4	1520
	11th to 20th	Day	62% 8% 12% 13% 4	1906
	21st to end	Day	75% 6% 9% 7% 2	2803
January	1st to 10th	Night	63% 6% 10% 14% 7%	2648
	11th to 20th	Night	69% 7% 11% 11% 3	2503
	21st to end	Night	65% 6% 11% 12% 6%	2711
February	1st to 10th	Night	64% 6% 11% 14% 5% 1	2340
	11th to 20th	Night	60% 6% 9% 16% 8% 1	2182
	21st to end	Night	57% 5% 11% 18% 8% 1	1776
March	1st to 10th	Night	50% 6% 12% 22% 10%	2078
	11th to 20th	Night	43% 7% 12% 21% 14% 2	1980
	21st to end	Night	51% 5% 8% 22% 11% 2	2178
April	1st to 10th	Night	48% 6% 11% 20% 14% 2	1949
	11th to 20th	Night	45% 6% 11% 18% 17% 3	1597
	21st to end	Night	45% 5% 10% 20% 16% 4	1620
May	1st to 10th	Night	51% 7% 10% 17% 12% 3	1620
	11th to 20th	Night	45% 6% 10% 18% 18% 4	1593
	21st to end	Night	33% 8% 13% 27% 17% 1	1745
June	1st to 10th	Night	36% 8% 10% 26% 16% 3	1453
	11th to 20th	Night	36% 8% 14% 23% 17% 3	1260
	21st to end	Night	34% 8% 11% 26% 21% 1	1335
July	1st to 10th	Night	31% 7% 12% 25% 22% 4	1400
	11th to 20th	Night	31% 8% 12% 29% 17% 3	1472
	21st to end	Night	28% 9% 17% 22% 20% 4	1672
August	1st to 10th	Night	30% 6% 15% 32% 16% 1	1600
	11th to 20th	Night	32% 10% 13% 29% 13% 3	1598
	21st to end	Night	32% 7% 13% 26% 19% 2	1782
September	1st to 10th	Night	35% 8% 13% 26% 14% 4	1919
	11th to 20th	Night	33% 7% 11% 26% 21% 1	1980
	21st to end	Night	42% 7% 11% 22% 17% 1	1980
October	1st to 10th	Night	41% 7% 13% 19% 20% 1	2061
	11th to 20th	Night	52% 7% 10% 16% 14% 1	2160
	21st to end	Night	56% 6% 11% 18% 9% 1	2452
November	1st to 10th	Night	46% 7% 11% 20% 15% 1	2406
	11th to 20th	Night	57% 6% 11% 16% 9% 1	2470
	21st to end	Night	60% 6% 12% 17% 5%	2623
December	1st to 10th	Night	71% 6% 8% 11% 4	2660
	11th to 20th	Night	62% 6% 16% 13% 4	3288
	21st to end	Night	77% 5% 9% 7% 2	4844

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	23% 10% 29% 28% 9% 1	270
	11th to 20th	Day	23% 10% 36% 26% 6% 1	270
	21st to end	Day	28% 6% 28% 29% 7% 1	294
February	1st to 10th	Day	25% 9% 30% 33% 3	240
	11th to 20th	Day	23% 6% 35% 30% 7%	240
	21st to end	Day	20% 7% 40% 29% 5%	198
March	1st to 10th	Day	20% 7% 27% 36% 11%	320
	11th to 20th	Day	17% 6% 30% 34% 11% 1	420
	21st to end	Day	22% 7% 26% 35% 9% 1	462
April	1st to 10th	Day	12% 7% 26% 38% 15% 1	420
	11th to 20th	Day	19% 6% 24% 33% 13% 5%	412
	21st to end	Day	20% 4 25% 35% 16% 1	420
May	1st to 10th	Day	23% 3 19% 32% 20% 4	423
	11th to 20th	Day	17% 3 17% 30% 27% 6%	447
	21st to end	Day	12% 10% 33% 33% 12%	485
June	1st to 10th	Day	11% 2 12% 37% 32% 5%	473
	11th to 20th	Day	10% 3 15% 35% 31% 7%	630
	21st to end	Day	11% 2 11% 36% 33% 7%	630
July	1st to 10th	Day	7% 2 9% 30% 35% 16%	621
	11th to 20th	Day	11% 3 7% 30% 40% 9%	534
	21st to end	Day	9% 2 7% 30% 41% 10%	488
August	1st to 10th	Day	8% 3 8% 31% 36% 14%	446
	11th to 20th	Day	11% 2 9% 27% 39% 13%	439
	21st to end	Day	8% 2 9% 30% 39% 12%	495
September	1st to 10th	Day	12% 2 12% 28% 31% 14%	450
	11th to 20th	Day	11% 2 10% 24% 37% 16%	450
	21st to end	Day	19% 5% 16% 23% 27% 10%	450
October	1st to 10th	Day	14% 3 21% 23% 26% 14%	450
	11th to 20th	Day	18% 10% 25% 29% 16% 2	450
	21st to end	Day	26% 9% 26% 27% 12% 2	415
November	1st to 10th	Day	15% 8% 25% 27% 21% 4	270
	11th to 20th	Day	22% 13% 26% 24% 13% 2	270
	21st to end	Day	24% 6% 37% 31% 3	196
December	1st to 10th	Day	20% 12% 32% 27% 9%	180
	11th to 20th	Day	27% 12% 36% 21% 4	180
	21st to end	Day	25% 11% 32% 27% 5%	263
January	1st to 10th	Night	25% 10% 34% 22% 8% 1	950
	11th to 20th	Night	27% 10% 34% 23% 6%	793
	21st to end	Night	24% 8% 31% 30% 7%	835
February	1st to 10th	Night	26% 7% 33% 30% 5%	720
	11th to 20th	Night	24% 7% 30% 32% 6%	703
	21st to end	Night	25% 7% 36% 29% 3	592
March	1st to 10th	Night	19% 7% 30% 34% 9% 1	720
	11th to 20th	Night	19% 6% 32% 32% 9% 2	720
	21st to end	Night	22% 6% 27% 31% 13% 2	792
April	1st to 10th	Night	18% 7% 29% 35% 10% 1	689
	11th to 20th	Night	19% 5% 27% 33% 14% 2	533
	21st to end	Night	18% 4 25% 36% 14% 2	540
May	1st to 10th	Night	19% 4 23% 35% 17% 3	540
	11th to 20th	Night	20% 4 16% 32% 24% 4	531
	21st to end	Night	10% 2 16% 29% 34% 9%	584
June	1st to 10th	Night	13% 1 19% 37% 27% 3	401
	11th to 20th	Night	11% 2 15% 37% 32% 3	360
	21st to end	Night	10% 2 15% 37% 31% 5%	435
July	1st to 10th	Night	10% 2 10% 31% 38% 9%	525
	11th to 20th	Night	10% 4 10% 34% 33% 8%	522
	21st to end	Night	7% 2 12% 38% 35% 5%	591
August	1st to 10th	Night	8% 1 11% 38% 32% 10%	537
	11th to 20th	Night	8% 2 13% 33% 34% 10%	534
	21st to end	Night	11% 1 12% 34% 33% 10%	594
September	1st to 10th	Night	13% 3 13% 28% 33% 9%	690
	11th to 20th	Night	11% 4 13% 30% 33% 10%	720
	21st to end	Night	18% 5% 17% 29% 24% 8%	720
October	1st to 10th	Night	18% 4 22% 26% 23% 7%	720
	11th to 20th	Night	23% 11% 27% 24% 14% 2	720
	21st to end	Night	27% 11% 28% 26% 7% 1	792
November	1st to 10th	Night	19% 10% 26% 28% 15% 2	740
	11th to 20th	Night	25% 13% 33% 19% 8% 2	760
	21st to end	Night	30% 12% 29% 21% 8%	760
December	1st to 10th	Night	28% 15% 30% 21% 6% 1	760
	11th to 20th	Night	25% 12% 36% 21% 6%	760
	21st to end	Night	29% 10% 33% 24% 4	950

Page generated at 2024-01-28 05:26:36. Version ac07

Copyright 2024 Attilla Danko