Port Hope Simpson Community Hall
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Port Hope Simpson Community Hall clear sky chart from 2005-11-06 to 2025-07-06.

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	21% 15% 4 8% 5% 4 4 3 4 5% 26%	120513
	Night	19% 15% 5% 8% 5% 4 4 3 4 5% 28%	118453
Transparency	Day	59% 6% 11% 16% 8% 1	123918
	Night	57% 6% 11% 16% 9% 1	123231
Seeing	Day	31% 15% 28% 18% 6% 2	18864
	Night	29% 14% 31% 20% 6% 1	25306

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	17% 22% 8% 10% 3 3 3 2 3 4 25%	2965
	11th to 20th	Day	16% 24% 8% 10% 5% 3 3 2 3 4 23%	3287
	21st to end	Day	5% 8% 3 6% 4 5% 5% 4 5% 7% 48%	3982
February	1st to 10th	Day	11% 12% 5% 8% 5% 5% 4 4 4 6% 36%	1600
	11th to 20th	Day	15% 20% 5% 9% 6% 3 4 2 4 5% 26%	1653
	21st to end	Day	13% 18% 4 7% 4 4 4 3 4 6% 32%	1650
March	1st to 10th	Day	13% 14% 5% 10% 5% 6% 6% 3 4 4 31%	4474
	11th to 20th	Day	15% 24% 8% 11% 5% 4 3 3 3 4 20%	4720
	21st to end	Day	24% 16% 6% 10% 5% 4 3 2 4 4 22%	5869
April	1st to 10th	Day	21% 20% 7% 9% 6% 3 4 2 5% 4 19%	2400
	11th to 20th	Day	19% 19% 6% 9% 5% 4 3 3 4 5% 24%	2560
	21st to end	Day	23% 18% 5% 8% 5% 4 3 2 4 3 24%	2680
May	1st to 10th	Day	30% 19% 4 8% 5% 3 3 3 3 4 19%	6345
	11th to 20th	Day	24% 22% 6% 10% 4 3 3 3 3 4 18%	6746
	21st to end	Day	28% 17% 3 7% 4 3 4 2 4 5% 23%	7428
June	1st to 10th	Day	33% 13% 4 7% 5% 4 4 3 4 5% 18%	3057
	11th to 20th	Day	32% 11% 2 7% 5% 4 4 4 5% 6% 20%	3200
	21st to end	Day	28% 11% 3 7% 5% 4 4 3 6% 6% 23%	3200
July	1st to 10th	Day	23% 9% 3 7% 4 4 4 4 6% 7% 30%	5150
	11th to 20th	Day	24% 12% 3 8% 5% 4 4 3 5% 6% 27%	4760
	21st to end	Day	16% 8% 3 8% 6% 6% 6% 5% 7% 8% 27%	4975
August	1st to 10th	Day	22% 12% 4 8% 5% 5% 5% 4 6% 7% 21%	4424
	11th to 20th	Day	24% 10% 3 9% 5% 4 4 3 6% 7% 25%	4274
	21st to end	Day	18% 8% 3 7% 5% 4 5% 4 5% 8% 34%	4532
September	1st to 10th	Day	26% 7% 2 7% 4 4 4 3 5% 7% 31%	2290
	11th to 20th	Day	24% 10% 3 7% 5% 5% 4 3 5% 6% 27%	2146
	21st to end	Day	25% 11% 2 7% 6% 4 5% 3 3 6% 28%	2090
October	1st to 10th	Day	24% 14% 3 7% 4 4 4 3 4 6% 27%	1985
	11th to 20th	Day	25% 15% 3 9% 5% 4 4 3 4 5% 24%	1710
	21st to end	Day	26% 17% 3 6% 4 3 4 2 5% 5% 26%	1881
November	1st to 10th	Day	18% 14% 3 6% 5% 5% 3 3 5% 6% 32%	1650
	11th to 20th	Day	20% 13% 2 7% 5% 4 4 3 5% 5% 33%	1400
	21st to end	Day	22% 19% 4 5% 4 3 3 3 4 4 29%	1400
December	1st to 10th	Day	11% 16% 6% 10% 6% 5% 3 3 3 6% 32%	2290
	11th to 20th	Day	17% 15% 6% 8% 4 4 4 4 4 6% 29%	2628
	21st to end	Day	18% 14% 5% 9% 6% 2 2 2 3 5% 34%	3112
January	1st to 10th	Night	20% 20% 6% 10% 4 3 3 2 3 4 24%	6993
	11th to 20th	Night	14% 21% 7% 10% 5% 4 4 3 4 5% 25%	6602
	21st to end	Night	6% 9% 3 7% 5% 4 4 3 5% 6% 49%	6996
February	1st to 10th	Night	11% 11% 4 10% 5% 4 4 3 4 6% 38%	2800
	11th to 20th	Night	14% 19% 6% 11% 6% 4 3 2 4 5% 26%	2628
	21st to end	Night	13% 16% 5% 8% 5% 3 5% 3 5% 5% 32%	1980
March	1st to 10th	Night	15% 14% 4 10% 5% 4 4 4 4 5% 31%	5366
	11th to 20th	Night	14% 22% 7% 9% 5% 4 3 3 3 4 26%	5239
	21st to end	Night	23% 14% 4 9% 5% 5% 4 3 4 5% 24%	5063
April	1st to 10th	Night	21% 18% 6% 9% 5% 4 4 3 5% 4 21%	2000
	11th to 20th	Night	20% 15% 5% 7% 5% 3 4 3 5% 5% 27%	1789
	21st to end	Night	22% 16% 5% 7% 5% 3 3 3 5% 4 28%	1719
May	1st to 10th	Night	31% 19% 5% 8% 3 4 4 3 5% 5% 14%	3615
	11th to 20th	Night	27% 17% 4 9% 4 3 3 2 3 4 25%	3166
	21st to end	Night	28% 17% 4 6% 4 3 3 2 4 4 25%	3468
June	1st to 10th	Night	31% 14% 3 7% 4 4 4 3 4 5% 21%	1359
	11th to 20th	Night	30% 15% 3 8% 4 4 4 4 5% 5% 18%	1200
	21st to end	Night	26% 10% 3 7% 5% 4 4 4 5% 5% 28%	1200
July	1st to 10th	Night	20% 10% 3 7% 6% 5% 5% 3 6% 6% 27%	1930
	11th to 20th	Night	24% 12% 3 7% 3 3 3 3 4 5% 33%	2174
	21st to end	Night	15% 8% 3 8% 6% 6% 6% 4 6% 7% 31%	2587
August	1st to 10th	Night	18% 11% 3 8% 6% 5% 5% 4 5% 7% 29%	2516
	11th to 20th	Night	23% 10% 3 7% 4 4 5% 3 5% 7% 28%	2563
	21st to end	Night	16% 7% 3 7% 6% 5% 5% 4 6% 6% 35%	3135
September	1st to 10th	Night	22% 8% 3 6% 5% 4 4 4 5% 7% 33%	1889
	11th to 20th	Night	23% 11% 3 7% 4 3 3 3 6% 6% 30%	2034
	21st to end	Night	24% 12% 4 7% 4 4 3 2 6% 6% 28%	2090
October	1st to 10th	Night	25% 13% 3 8% 4 4 4 2 5% 6% 28%	2191
	11th to 20th	Night	24% 14% 4 6% 4 4 4 3 4 6% 27%	2470
	21st to end	Night	26% 18% 4 7% 4 4 3 3 3 5% 23%	2717
November	1st to 10th	Night	20% 13% 3 7% 5% 4 5% 3 5% 6% 29%	2645
	11th to 20th	Night	22% 13% 3 6% 4 4 4 3 4 5% 32%	3000
	21st to end	Night	22% 19% 5% 6% 3 3 3 3 4 4 28%	3000
December	1st to 10th	Night	12% 13% 6% 11% 6% 5% 5% 3 5% 4 29%	4900
	11th to 20th	Night	19% 12% 4 10% 6% 5% 4 3 5% 5% 26%	5581
	21st to end	Night	16% 14% 6% 10% 6% 4 3 3 4 6% 29%	7848

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% 4 7% 13% 10% 1	2966
	11th to 20th	Day	65% 5% 14% 10% 6%	3312
	21st to end	Day	34% 4 14% 25% 19% 4	3982
February	1st to 10th	Day	50% 3 9% 21% 15% 3	1600
	11th to 20th	Day	60% 4 6% 17% 12% 1	1660
	21st to end	Day	53% 5% 7% 18% 16% 1	1650
March	1st to 10th	Day	55% 5% 6% 14% 16% 2	4478
	11th to 20th	Day	68% 4 6% 9% 10% 3	4720
	21st to end	Day	65% 4 5% 12% 12% 2	5869
April	1st to 10th	Day	68% 5% 6% 12% 8% 2	2400
	11th to 20th	Day	63% 5% 9% 13% 9% 1	2560
	21st to end	Day	64% 4 10% 15% 7% 1	2680
May	1st to 10th	Day	70% 5% 8% 11% 6%	6357
	11th to 20th	Day	69% 6% 8% 12% 4	6750
	21st to end	Day	64% 5% 11% 17% 2	7428
June	1st to 10th	Day	69% 6% 10% 10% 5%	3057
	11th to 20th	Day	64% 7% 13% 13% 4	3200
	21st to end	Day	60% 7% 11% 16% 6%	3200
July	1st to 10th	Day	49% 8% 13% 20% 10%	5070
	11th to 20th	Day	56% 7% 14% 15% 7% 1	4677
	21st to end	Day	50% 10% 16% 20% 5%	4816
August	1st to 10th	Day	59% 8% 15% 16% 2	4410
	11th to 20th	Day	56% 7% 13% 18% 5%	4316
	21st to end	Day	47% 6% 16% 24% 6%	4532
September	1st to 10th	Day	53% 5% 14% 20% 8% 1	2290
	11th to 20th	Day	57% 6% 12% 17% 7% 1	2146
	21st to end	Day	57% 6% 13% 18% 6% 1	2090
October	1st to 10th	Day	52% 7% 11% 23% 6%	3299
	11th to 20th	Day	61% 6% 14% 14% 6%	2832
	21st to end	Day	62% 6% 10% 13% 8% 1	3092
November	1st to 10th	Day	52% 5% 11% 20% 10% 1	1650
	11th to 20th	Day	53% 5% 13% 20% 9% 1	1400
	21st to end	Day	59% 4 10% 16% 12%	1400
December	1st to 10th	Day	53% 6% 10% 21% 10%	2290
	11th to 20th	Day	55% 9% 11% 15% 9% 1	2627
	21st to end	Day	54% 4 14% 15% 13% 1	3112
January	1st to 10th	Night	64% 5% 7% 12% 11% 2	6993
	11th to 20th	Night	62% 5% 14% 13% 6% 1	6651
	21st to end	Night	36% 4 11% 23% 20% 6%	6996
February	1st to 10th	Night	48% 4 11% 22% 13% 2	2800
	11th to 20th	Night	62% 4 9% 15% 9% 2	2632
	21st to end	Night	53% 3 9% 20% 13% 2	1980
March	1st to 10th	Night	55% 5% 8% 13% 18% 2	5375
	11th to 20th	Night	63% 4 5% 13% 13% 2	5240
	21st to end	Night	61% 6% 7% 15% 10% 1	5063
April	1st to 10th	Night	65% 5% 7% 12% 9% 2	2000
	11th to 20th	Night	58% 5% 11% 16% 10% 1	1789
	21st to end	Night	59% 5% 12% 15% 9% 1	1719
May	1st to 10th	Night	72% 5% 10% 9% 4	3620
	11th to 20th	Night	64% 5% 10% 15% 6%	3167
	21st to end	Night	64% 4 11% 18% 3	3469
June	1st to 10th	Night	64% 6% 9% 15% 6%	1359
	11th to 20th	Night	66% 7% 13% 11% 3	1200
	21st to end	Night	56% 8% 12% 18% 5%	1200
July	1st to 10th	Night	56% 7% 13% 17% 7%	1900
	11th to 20th	Night	54% 6% 12% 24% 4	2134
	21st to end	Night	49% 9% 19% 20% 4	2506
August	1st to 10th	Night	53% 9% 19% 16% 2	2505
	11th to 20th	Night	55% 7% 18% 15% 4	2587
	21st to end	Night	47% 8% 17% 23% 5%	3134
September	1st to 10th	Night	49% 7% 16% 21% 7%	1889
	11th to 20th	Night	53% 6% 14% 20% 6% 1	2034
	21st to end	Night	56% 6% 14% 18% 6% 1	2090
October	1st to 10th	Night	63% 5% 10% 16% 5%	3659
	11th to 20th	Night	60% 8% 9% 15% 8%	4097
	21st to end	Night	61% 6% 11% 14% 7%	4467
November	1st to 10th	Night	54% 6% 12% 18% 9% 1	2645
	11th to 20th	Night	54% 5% 13% 20% 7% 1	3000
	21st to end	Night	60% 5% 9% 16% 9% 1	3000
December	1st to 10th	Night	55% 7% 11% 18% 9% 1	4900
	11th to 20th	Night	57% 8% 13% 12% 9% 1	5583
	21st to end	Night	56% 5% 12% 17% 9% 1	7848

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	28% 16% 27% 20% 6% 3	305
	11th to 20th	Day	21% 21% 33% 17% 8% 1	400
	21st to end	Day	19% 20% 35% 21% 4	440
February	1st to 10th	Day	19% 15% 40% 19% 5% 2	400
	11th to 20th	Day	24% 21% 37% 14% 2 1	396
	21st to end	Day	25% 19% 34% 14% 6% 1	331
March	1st to 10th	Day	25% 22% 28% 19% 5% 1	400
	11th to 20th	Day	25% 16% 30% 20% 8% 2	400
	21st to end	Day	30% 22% 29% 13% 4 1	526
April	1st to 10th	Day	34% 19% 27% 13% 6% 2	500
	11th to 20th	Day	28% 18% 29% 18% 5% 2	678
	21st to end	Day	30% 18% 26% 18% 7% 2	700
May	1st to 10th	Day	41% 10% 22% 18% 6% 2	703
	11th to 20th	Day	39% 13% 22% 16% 7% 3	724
	21st to end	Day	40% 13% 25% 15% 5% 1	790
June	1st to 10th	Day	41% 13% 23% 16% 6% 2	730
	11th to 20th	Day	40% 11% 26% 14% 6% 3	730
	21st to end	Day	35% 12% 27% 15% 8% 3	730
July	1st to 10th	Day	32% 12% 25% 19% 10% 2	695
	11th to 20th	Day	26% 9% 32% 24% 8% 1	668
	21st to end	Day	25% 11% 25% 27% 10% 2	740
August	1st to 10th	Day	30% 9% 25% 24% 11% 2	675
	11th to 20th	Day	28% 9% 29% 21% 11% 1	667
	21st to end	Day	28% 13% 27% 20% 9% 3	748
September	1st to 10th	Day	31% 18% 31% 16% 4 1	500
	11th to 20th	Day	29% 15% 35% 15% 5% 1	419
	21st to end	Day	33% 16% 30% 16% 4 2	390
October	1st to 10th	Day	33% 17% 30% 16% 3 1	390
	11th to 20th	Day	32% 15% 27% 18% 7% 1	390
	21st to end	Day	35% 18% 22% 17% 7% 1	429
November	1st to 10th	Day	29% 24% 34% 10% 3	395
	11th to 20th	Day	31% 16% 30% 17% 6% 1	400
	21st to end	Day	35% 16% 27% 18% 5%	400
December	1st to 10th	Day	30% 19% 28% 18% 5% 1	400
	11th to 20th	Day	34% 16% 36% 12% 2 1	400
	21st to end	Day	24% 13% 38% 16% 7% 2	275
January	1st to 10th	Night	28% 18% 32% 16% 6% 1	900
	11th to 20th	Night	22% 18% 33% 20% 6%	900
	21st to end	Night	24% 18% 37% 18% 3	990
February	1st to 10th	Night	19% 17% 36% 21% 5% 1	900
	11th to 20th	Night	25% 18% 35% 17% 4	860
	21st to end	Night	22% 15% 35% 21% 6% 2	660
March	1st to 10th	Night	26% 19% 30% 20% 5% 1	800
	11th to 20th	Night	23% 16% 31% 23% 7%	717
	21st to end	Night	29% 17% 31% 18% 4 1	660
April	1st to 10th	Night	30% 16% 27% 19% 7% 1	600
	11th to 20th	Night	29% 15% 30% 17% 7% 2	594
	21st to end	Night	33% 12% 27% 20% 8% 1	600
May	1st to 10th	Night	36% 9% 23% 23% 8% 1	600
	11th to 20th	Night	34% 9% 26% 21% 9% 2	592
	21st to end	Night	39% 11% 26% 15% 8%	649
June	1st to 10th	Night	38% 9% 25% 21% 7%	559
	11th to 20th	Night	38% 9% 23% 21% 10% 1	400
	21st to end	Night	32% 8% 24% 24% 11% 2	400
July	1st to 10th	Night	28% 9% 28% 25% 9% 1	380
	11th to 20th	Night	26% 8% 36% 24% 6%	521
	21st to end	Night	27% 6% 28% 31% 8%	623
August	1st to 10th	Night	27% 7% 28% 29% 9%	568
	11th to 20th	Night	27% 8% 30% 27% 8% 1	562
	21st to end	Night	23% 9% 29% 28% 10% 1	627
September	1st to 10th	Night	26% 12% 35% 23% 4	570
	11th to 20th	Night	29% 14% 32% 19% 5%	570
	21st to end	Night	31% 15% 28% 20% 4 1	570
October	1st to 10th	Night	32% 14% 31% 19% 3 1	658
	11th to 20th	Night	31% 12% 27% 23% 6%	860
	21st to end	Night	36% 14% 27% 17% 5%	946
November	1st to 10th	Night	29% 19% 33% 15% 4	880
	11th to 20th	Night	31% 17% 29% 17% 5% 1	900
	21st to end	Night	34% 20% 28% 14% 3	900
December	1st to 10th	Night	26% 17% 35% 18% 5%	900
	11th to 20th	Night	27% 17% 36% 16% 3	900
	21st to end	Night	24% 18% 32% 19% 5% 1	990

Page generated at 2025-07-03 02:30:17. Version ac07

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