Port Burwell Provincial Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Port Burwell Provincial Park clear sky chart from 2005-11-06 to 2024-08-15.

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	15% 9% 3 8% 5% 5% 5% 4 6% 7% 34%	95751
	Night	16% 10% 4 8% 5% 4 4 4 5% 7% 33%	92926
Transparency	Day	25% 52% 7% 10% 5% 1	95484
	Night	26% 52% 6% 10% 5% 1	92748
Seeing	Day	18% 10% 27% 26% 14% 5%	14490
	Night	20% 9% 28% 29% 13% 2	23746

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	19% 16% 8% 12% 5% 5% 4 3 4 4 21%	2691
	11th to 20th	Day	13% 21% 7% 19% 10% 7% 4 3 3 3 10%	2840
	21st to end	Day	24% 20% 6% 11% 5% 4 5% 3 4 4 15%	3124
February	1st to 10th	Day	17% 17% 5% 12% 5% 6% 4 4 5% 5% 20%	1710
	11th to 20th	Day	15% 13% 8% 12% 6% 5% 4 4 4 5% 24%	1663
	21st to end	Day	19% 13% 4 10% 6% 4 5% 4 5% 6% 24%	1551
March	1st to 10th	Day	22% 11% 4 10% 6% 5% 4 4 5% 5% 27%	3388
	11th to 20th	Day	12% 14% 4 9% 6% 4 4 3 5% 8% 31%	3480
	21st to end	Day	19% 8% 3 7% 5% 5% 5% 3 5% 6% 35%	3815
April	1st to 10th	Day	16% 10% 3 8% 5% 4 5% 4 6% 8% 31%	2175
	11th to 20th	Day	17% 9% 4 7% 5% 4 3 3 6% 6% 34%	2390
	21st to end	Day	19% 9% 3 7% 4 4 4 4 5% 7% 36%	2470
May	1st to 10th	Day	20% 7% 3 7% 5% 4 5% 4 5% 7% 32%	4108
	11th to 20th	Day	17% 10% 3 7% 5% 4 4 4 5% 8% 33%	4108
	21st to end	Day	11% 4 2 6% 4 4 4 3 6% 9% 46%	4837
June	1st to 10th	Day	12% 6% 2 6% 4 4 5% 4 7% 8% 41%	2660
	11th to 20th	Day	10% 5% 2 6% 5% 4 4 5% 8% 9% 40%	2691
	21st to end	Day	11% 5% 2 6% 4 4 5% 4 7% 10% 43%	2850
July	1st to 10th	Day	9% 4 2 5% 4 4 5% 4 7% 9% 45%	4614
	11th to 20th	Day	10% 5% 2 6% 4 3 5% 4 7% 10% 46%	4155
	21st to end	Day	7% 4 2 6% 4 5% 5% 5% 7% 10% 45%	4466
August	1st to 10th	Day	9% 5% 2 4 4 4 5% 5% 8% 10% 43%	2457
	11th to 20th	Day	10% 3 2 5% 5% 5% 6% 6% 8% 10% 40%	2357
	21st to end	Day	10% 7% 2 6% 4 3 4 4 6% 9% 44%	2520
September	1st to 10th	Day	12% 5% 2 6% 4 6% 5% 4 6% 9% 42%	2134
	11th to 20th	Day	9% 5% 2 5% 4 4 5% 4 6% 8% 47%	1980
	21st to end	Day	16% 6% 2 6% 4 5% 5% 4 6% 7% 39%	1980
October	1st to 10th	Day	16% 8% 3 6% 5% 5% 5% 4 5% 7% 37%	1823
	11th to 20th	Day	20% 9% 3 8% 5% 5% 6% 4 5% 7% 29%	1800
	21st to end	Day	24% 11% 3 9% 5% 4 5% 4 5% 6% 24%	1980
November	1st to 10th	Day	14% 8% 2 7% 5% 5% 5% 5% 6% 6% 36%	1672
	11th to 20th	Day	16% 13% 4 8% 4 4 5% 3 6% 7% 30%	1544
	21st to end	Day	22% 13% 5% 9% 6% 5% 4 4 5% 6% 20%	1520
December	1st to 10th	Day	19% 17% 5% 11% 7% 4 4 4 5% 6% 19%	1520
	11th to 20th	Day	19% 16% 7% 10% 6% 5% 5% 4 5% 5% 18%	1906
	21st to end	Day	30% 18% 5% 8% 5% 4 4 3 4 5% 12%	2772
January	1st to 10th	Night	19% 18% 7% 10% 5% 5% 4 4 4 4 20%	4237
	11th to 20th	Night	17% 19% 7% 14% 7% 11% 4 3 4 3 12%	4120
	21st to end	Night	25% 18% 7% 15% 5% 4 3 2 4 4 13%	4532
February	1st to 10th	Night	17% 16% 4 10% 7% 5% 5% 3 5% 5% 22%	2470
	11th to 20th	Night	16% 14% 4 9% 5% 5% 4 4 6% 6% 25%	2403
	21st to end	Night	19% 12% 4 9% 6% 5% 4 4 5% 7% 24%	1902
March	1st to 10th	Night	20% 10% 4 7% 6% 4 4 3 4 6% 32%	3450
	11th to 20th	Night	13% 10% 3 6% 5% 4 4 4 5% 8% 38%	3479
	21st to end	Night	16% 11% 3 7% 4 4 4 4 4 5% 39%	3817
April	1st to 10th	Night	20% 9% 3 7% 4 4 4 4 5% 6% 33%	2005
	11th to 20th	Night	17% 8% 3 8% 5% 4 4 4 5% 7% 36%	1754
	21st to end	Night	16% 6% 2 8% 5% 5% 5% 4 5% 7% 36%	1710
May	1st to 10th	Night	21% 8% 2 7% 4 3 3 3 5% 6% 37%	2833
	11th to 20th	Night	12% 7% 3 8% 6% 6% 6% 4 6% 6% 37%	2785
	21st to end	Night	12% 4 2 4 4 3 4 4 6% 9% 48%	2738
June	1st to 10th	Night	12% 6% 2 5% 5% 4 4 4 6% 8% 44%	1520
	11th to 20th	Night	10% 5% 2 5% 4 5% 5% 4 7% 10% 42%	1478
	21st to end	Night	10% 5% 2 6% 3 4 4 4 6% 9% 46%	1330
July	1st to 10th	Night	8% 4 2 5% 4 4 3 4 6% 10% 50%	2329
	11th to 20th	Night	9% 4 2 5% 4 4 3 4 6% 9% 50%	2800
	21st to end	Night	6% 4 2 6% 4 4 5% 5% 6% 9% 49%	3087
August	1st to 10th	Night	8% 4 1 5% 5% 4 5% 4 8% 9% 46%	1701
	11th to 20th	Night	8% 4 2 5% 4 4 4 3 7% 10% 49%	1643
	21st to end	Night	10% 4 2 6% 4 4 4 3 5% 8% 48%	1818
September	1st to 10th	Night	10% 7% 2 6% 3 4 5% 4 6% 8% 45%	1822
	11th to 20th	Night	11% 5% 2 4 3 4 4 4 6% 6% 52%	1980
	21st to end	Night	15% 5% 2 7% 5% 5% 4 4 5% 7% 41%	1980
October	1st to 10th	Night	15% 6% 2 7% 4 4 4 4 6% 7% 42%	2137
	11th to 20th	Night	18% 10% 3 8% 5% 5% 4 3 6% 6% 34%	2160
	21st to end	Night	24% 10% 3 7% 5% 4 4 4 5% 6% 29%	2376
November	1st to 10th	Night	16% 6% 2 6% 4 4 4 3 7% 6% 40%	2403
	11th to 20th	Night	17% 10% 3 8% 6% 5% 5% 4 6% 7% 28%	2635
	21st to end	Night	22% 14% 4 7% 6% 4 5% 4 5% 7% 24%	2660
December	1st to 10th	Night	22% 15% 4 9% 6% 4 4 3 5% 7% 20%	2660
	11th to 20th	Night	17% 18% 6% 10% 6% 4 4 3 5% 6% 21%	3288
	21st to end	Night	29% 19% 5% 9% 5% 4 4 3 4 4 14%	4884

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	44% 41% 4 6% 5%	2692
	11th to 20th	Day	52% 40% 3 3 2	2840
	21st to end	Day	47% 43% 6% 3 1	3124
February	1st to 10th	Day	24% 65% 3 5% 2	1710
	11th to 20th	Day	23% 64% 2 8% 3	1672
	21st to end	Day	21% 66% 4 6% 3 1	1551
March	1st to 10th	Day	38% 43% 3 13% 2	3391
	11th to 20th	Day	30% 41% 14% 11% 3	3480
	21st to end	Day	28% 42% 8% 13% 8% 1	3815
April	1st to 10th	Day	22% 65% 3 6% 3	2175
	11th to 20th	Day	18% 66% 3 8% 4 1	2390
	21st to end	Day	19% 66% 4 6% 5% 1	2470
May	1st to 10th	Day	32% 42% 9% 11% 5% 2	4120
	11th to 20th	Day	30% 46% 11% 11% 1	4112
	21st to end	Day	21% 43% 7% 13% 12% 4	4837
June	1st to 10th	Day	15% 66% 4 9% 6% 1	2660
	11th to 20th	Day	15% 66% 5% 7% 6% 1	2691
	21st to end	Day	13% 64% 5% 10% 8%	2850
July	1st to 10th	Day	24% 37% 9% 18% 10% 2	4544
	11th to 20th	Day	20% 37% 10% 24% 9%	4084
	21st to end	Day	20% 38% 12% 15% 14% 1	4324
August	1st to 10th	Day	13% 61% 7% 12% 5% 1	2444
	11th to 20th	Day	15% 65% 7% 12% 1	2357
	21st to end	Day	13% 64% 5% 11% 6% 1	2520
September	1st to 10th	Day	14% 64% 7% 10% 5%	2134
	11th to 20th	Day	12% 64% 5% 11% 8%	1980
	21st to end	Day	14% 63% 6% 11% 6%	1980
October	1st to 10th	Day	19% 63% 5% 7% 5%	1823
	11th to 20th	Day	20% 64% 5% 7% 4	1800
	21st to end	Day	23% 62% 5% 7% 3	1980
November	1st to 10th	Day	24% 59% 5% 8% 3 1	1672
	11th to 20th	Day	21% 60% 6% 8% 4	1544
	21st to end	Day	26% 61% 7% 5% 2	1520
December	1st to 10th	Day	27% 61% 4 7% 1	1520
	11th to 20th	Day	36% 50% 7% 5% 2	1906
	21st to end	Day	48% 40% 7% 4 1	2772
January	1st to 10th	Night	42% 43% 6% 7% 2	4237
	11th to 20th	Night	47% 45% 3 3 1	4120
	21st to end	Night	51% 40% 4 4 1	4532
February	1st to 10th	Night	22% 65% 4 6% 2	2470
	11th to 20th	Night	20% 64% 4 8% 4	2405
	21st to end	Night	21% 65% 3 6% 3 1	1902
March	1st to 10th	Night	34% 42% 8% 12% 5%	3460
	11th to 20th	Night	25% 42% 13% 12% 8% 1	3480
	21st to end	Night	26% 42% 9% 11% 11% 1	3817
April	1st to 10th	Night	21% 65% 3 7% 3	2005
	11th to 20th	Night	18% 66% 3 7% 5% 1	1754
	21st to end	Night	15% 65% 4 9% 5% 1	1710
May	1st to 10th	Night	29% 41% 7% 11% 8% 3	2840
	11th to 20th	Night	29% 44% 9% 14% 3	2786
	21st to end	Night	20% 41% 8% 13% 16% 2	2739
June	1st to 10th	Night	14% 64% 4 11% 6% 1	1520
	11th to 20th	Night	13% 65% 5% 11% 5% 1	1478
	21st to end	Night	13% 64% 5% 9% 8%	1330
July	1st to 10th	Night	20% 37% 9% 18% 12% 5%	2291
	11th to 20th	Night	20% 37% 9% 23% 10% 1	2748
	21st to end	Night	21% 38% 11% 14% 14% 2	2988
August	1st to 10th	Night	12% 61% 6% 14% 6% 1	1690
	11th to 20th	Night	14% 63% 6% 14% 3	1643
	21st to end	Night	13% 64% 6% 10% 6%	1818
September	1st to 10th	Night	13% 63% 6% 10% 7%	1822
	11th to 20th	Night	11% 64% 4 12% 9% 1	1980
	21st to end	Night	14% 63% 5% 12% 6%	1980
October	1st to 10th	Night	16% 63% 5% 9% 7%	2137
	11th to 20th	Night	19% 64% 4 8% 5%	2160
	21st to end	Night	21% 62% 3 9% 4	2376
November	1st to 10th	Night	22% 59% 5% 8% 5%	2403
	11th to 20th	Night	20% 60% 4 12% 4	2635
	21st to end	Night	25% 61% 7% 5% 2	2660
December	1st to 10th	Night	25% 60% 6% 7% 2	2660
	11th to 20th	Night	32% 51% 6% 8% 2	3288
	21st to end	Night	49% 39% 7% 4 1	4884

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	26% 18% 32% 16% 7% 2	231
	11th to 20th	Day	26% 15% 38% 14% 5% 1	270
	21st to end	Day	26% 16% 33% 20% 4 1	297
February	1st to 10th	Day	22% 17% 42% 14% 4	270
	11th to 20th	Day	25% 22% 37% 15% 1	270
	21st to end	Day	27% 24% 38% 10% 1	225
March	1st to 10th	Day	24% 13% 32% 23% 7% 1	427
	11th to 20th	Day	22% 14% 35% 23% 4 1	460
	21st to end	Day	29% 13% 32% 19% 6% 1	506
April	1st to 10th	Day	18% 18% 33% 23% 6% 1	460
	11th to 20th	Day	25% 14% 29% 20% 9% 4	452
	21st to end	Day	23% 9% 34% 23% 8% 3	460
May	1st to 10th	Day	24% 10% 28% 23% 11% 4	463
	11th to 20th	Day	19% 9% 24% 28% 16% 5%	487
	21st to end	Day	13% 6% 22% 32% 22% 6%	529
June	1st to 10th	Day	13% 6% 31% 32% 15% 3	490
	11th to 20th	Day	12% 9% 23% 33% 19% 4	521
	21st to end	Day	14% 6% 29% 34% 14% 3	680
July	1st to 10th	Day	8% 4 21% 31% 26% 10%	594
	11th to 20th	Day	15% 4 22% 31% 18% 10%	484
	21st to end	Day	10% 2 20% 36% 23% 8%	532
August	1st to 10th	Day	9% 4 20% 33% 22% 13%	486
	11th to 20th	Day	12% 4 15% 34% 23% 12%	456
	21st to end	Day	13% 3 18% 34% 23% 10%	495
September	1st to 10th	Day	13% 4 20% 30% 21% 12%	450
	11th to 20th	Day	7% 5% 17% 28% 30% 13%	450
	21st to end	Day	16% 9% 23% 30% 15% 8%	450
October	1st to 10th	Day	20% 8% 24% 24% 20% 6%	450
	11th to 20th	Day	19% 17% 30% 25% 7% 2	450
	21st to end	Day	27% 12% 31% 22% 7%	495
November	1st to 10th	Day	17% 17% 34% 19% 9% 3	270
	11th to 20th	Day	26% 21% 28% 17% 7% 2	192
	21st to end	Day	28% 17% 34% 18% 3	180
December	1st to 10th	Day	29% 17% 32% 16% 6% 1	180
	11th to 20th	Day	27% 21% 33% 16% 3	180
	21st to end	Day	29% 21% 30% 17% 4	198
January	1st to 10th	Night	25% 17% 36% 15% 7%	760
	11th to 20th	Night	30% 14% 31% 22% 3	760
	21st to end	Night	23% 12% 35% 24% 6%	836
February	1st to 10th	Night	25% 15% 34% 23% 3	760
	11th to 20th	Night	23% 13% 34% 26% 4	743
	21st to end	Night	25% 12% 37% 22% 3	628
March	1st to 10th	Night	21% 9% 36% 26% 8%	760
	11th to 20th	Night	20% 8% 38% 26% 7%	760
	21st to end	Night	22% 9% 31% 28% 9% 1	836
April	1st to 10th	Night	23% 10% 34% 27% 6% 1	760
	11th to 20th	Night	22% 9% 31% 28% 9% 1	630
	21st to end	Night	18% 6% 31% 35% 9% 1	570
May	1st to 10th	Night	22% 4 26% 32% 15% 2	570
	11th to 20th	Night	16% 4 24% 41% 13% 2	547
	21st to end	Night	13% 3 23% 36% 22% 3	411
June	1st to 10th	Night	15% 1 27% 40% 16% 1	380
	11th to 20th	Night	12% 3 24% 42% 20%	380
	21st to end	Night	13% 4 21% 41% 19% 1	380
July	1st to 10th	Night	7% 3 18% 42% 26% 4	370
	11th to 20th	Night	12% 3 14% 41% 28% 4	527
	21st to end	Night	8% 2 16% 45% 26% 3	624
August	1st to 10th	Night	9% 2 14% 41% 30% 4	567
	11th to 20th	Night	10% 2 14% 36% 34% 4	549
	21st to end	Night	10% 3 16% 40% 27% 4	630
September	1st to 10th	Night	15% 4 17% 34% 25% 5%	720
	11th to 20th	Night	12% 3 14% 36% 30% 5%	720
	21st to end	Night	16% 5% 23% 30% 20% 6%	720
October	1st to 10th	Night	19% 6% 22% 32% 18% 4	720
	11th to 20th	Night	21% 12% 29% 27% 10% 1	720
	21st to end	Night	26% 11% 29% 28% 6%	792
November	1st to 10th	Night	19% 11% 27% 29% 13% 1	740
	11th to 20th	Night	22% 15% 32% 21% 8% 1	760
	21st to end	Night	28% 12% 31% 23% 7%	760
December	1st to 10th	Night	31% 16% 31% 16% 6% 1	760
	11th to 20th	Night	25% 16% 35% 19% 4	760
	21st to end	Night	31% 12% 32% 23% 2	836

Page generated at 2024-08-12 09:52:50. Version ac07

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