NAME
Weather::Meteo - Interface to https://open-meteo.com for historical weather data
VERSION
Version 0.13
SYNOPSIS
The Weather::Meteo module provides an interface to the Open-Meteo API for retrieving historical weather data from 1940.
It allows users to fetch weather information by specifying latitude, longitude, and a date.
The module supports object-oriented usage and allows customization of the HTTP user agent.
use Weather::Meteo;
my $meteo = Weather::Meteo->new();
my $weather = $meteo->weather({ latitude => 0.1, longitude => 0.2, date => '2022-12-25' });
-
Caching
Identical requests are cached (using CHI or a user-supplied caching object), reducing the number of HTTP requests to the API and speeding up repeated queries.
This module leverages CHI for caching geocoding responses. When a geocode request is made, a cache key is constructed from the request. If a cached response exists, it is returned immediately, avoiding unnecessary API calls.
-
Rate-Limiting
A minimum interval between successive API calls can be enforced to ensure that the API is not overwhelmed and to comply with any request throttling requirements.
Rate-limiting is implemented using Time::HiRes. A minimum interval between API calls can be specified via the
min_intervalparameter in the constructor. Before making an API call, the module checks how much time has elapsed since the last request and, if necessary, sleeps for the remaining time.
METHODS
new
my $meteo = Weather::Meteo->new();
my $ua = LWP::UserAgent->new();
$ua->env_proxy(1);
$meteo = Weather::Meteo->new(ua => $ua);
my $weather = $meteo->weather({ latitude => 51.34, longitude => 1.42, date => '2022-12-25' });
my @snowfall = @{$weather->{'hourly'}->{'snowfall'}};
print 'Number of cms of snow: ', $snowfall[1], "\n";
Creates a new instance. Acceptable options include:
-
cacheA caching object. If not provided, an in-memory cache is created with a default expiration of one hour.
-
hostThe API host endpoint. Defaults to https://archive-api.open-meteo.com.
-
min_intervalMinimum number of seconds to wait between API requests. Defaults to
0(no delay). Use this option to enforce rate-limiting. -
uaAn object to use for HTTP requests. If not provided, a default user agent is created.
The class can be configured at runtime using environments and configuration files,
for example,
setting $ENV{'WEATHER__METEO__carp_on_warn'} causes warnings to use Carp.
For more information about runtime configuration,
see Object::Configure.
API specification
Input
All parameters are optional.
They may be supplied as a hashref or a flat key/value list.
When $class is an existing Weather::Meteo object the call clones it,
merging any supplied parameters.
{
ua => { type => 'object', can => 'get', optional => 1 },
cache => { type => 'object', optional => 1 },
host => { type => 'scalar', optional => 1 },
min_interval => { type => 'scalar', optional => 1 },
}
Output
{ type => 'object', isa => 'Weather::Meteo' }
FORMAL SPECIFICATION
___ NEW ___________________________________________________
| class? : PACKAGE | Weather::Meteo |
| params? : NAME |--> VALUE |
|___________________________________________________________|
| result! : Weather::Meteo |
| |
| blessed(result!) = 'Weather::Meteo' |
| |
| params?.ua? => result!.ua = params?.ua |
| ~params?.ua => result!.ua : LWP::UserAgent |
| params?.cache? => result!.cache = params?.cache |
| ~params?.cache => result!.cache : CHI(Memory, global) |
| params?.host? => result!.host = params?.host |
| ~params?.host => result!.host = 'archive-api.open-meteo.com' |
| params?.min_interval? => result!.min_interval = params?.min_interval |
| ~params?.min_interval => result!.min_interval = 0 |
| result!.last_request = 0 |
|___________________________________________________________|
| |
| PRE: class? is PACKAGE name or blessed Weather::Meteo |
| POST: blessed(result!) = 'Weather::Meteo' |
| forall k in params? . result!.k = params?.k |
|___________________________________________________________|
weather
use Geo::Location::Point;
my $ramsgate = Geo::Location::Point->new({ latitude => 51.34, longitude => 1.42 });
# Print snowfall at 1AM on Christmas morning in Ramsgate
$weather = $meteo->weather($ramsgate, '2022-12-25');
@snowfall = @{$weather->{'hourly'}->{'snowfall'}};
print 'Number of cms of snow: ', $snowfall[1], "\n";
use DateTime;
my $dt = DateTime->new(year => 2024, month => 2, day => 1);
$weather = $meteo->weather({ location => $ramsgate, date => $dt });
The date argument can be an ISO-8601 formatted date, or an object that understands the strftime method.
Takes an optional argument, tz, containing the time zone. If not given, the module tries to work it out from the given location, for that to work set TIMEZONEDB_KEY to be your API key from https://timezonedb.com. If all else fails, the module falls back to Europe/London.
Dates before 1940 return undef silently.
Invalid date strings cause a carp and return undef.
Missing required arguments or non-numeric coordinates cause a croak.
On success returns a hashref containing at minimum the key hourly.
Returns undef if the API returns an error, if the JSON cannot be
parsed, or if the response contains no hourly key.
API specification
Input
Three call forms are accepted.
# Form 1 and 2 -- hashref or flat list
{
latitude => { type => 'scalar' },
longitude => { type => 'scalar' },
date => { type => 'scalar | object' },
tz => { type => 'scalar', optional => 1 },
location => { type => 'object', can => 'latitude', optional => 1 },
}
# Form 3 -- positional: ($location_obj, $date)
# $location_obj must respond to latitude() and longitude()
Output
{ type => 'hashref', min => 1 } # success -- contains 'hourly' key
undef # pre-1940 date, bad input, or API error
FORMAL SPECIFICATION
___ WEATHER _______________________________________________
| self? : Weather::Meteo |
| latitude? : REAL |
| longitude? : REAL |
| date? : DATE_STRING | strftime_OBJECT |
| tz? : STRING (optional, default 'Europe/London')|
|____________________________________________________________|
| result! : HASHREF | undef |
|____________________________________________________________|
| |
| PRE (~latitude? v ~longitude? v ~date?) |
| => croak /Usage: weather\(latitude/ |
| |
| PRE lat? or lon? not matching /^-?\d+(\.\d+)?$/ |
| (after leading-decimal normalisation) |
| => croak /Invalid latitude\/longitude format/ |
| |
| PRE date? blessed ^ date?.can('strftime') |
| => date? := date?.strftime('%F') |
| PRE date? !~ /^\d{4}-\d{2}-\d{2}$/ |
| => croak /Invalid date format. Expected YYYY-MM-DD/ |
| |
| PRE year(date?) < 1940 |
| => result! = undef |
| |
| POST cache hit for (lat, lon, date, tz) |
| => result! = cached_value |
| |
| POST HTTP error response |
| => carp msg ^ result! = undef |
| |
| POST JSON parse failure |
| => carp /Failed to parse JSON response/ ^ result! = undef |
| |
| POST response.error = true |
| => result! = undef |
| |
| POST ~response.hourly |
| => result! = undef |
| |
| POST otherwise |
| => result! = { hourly => HOURLY, daily => DAILY } |
| cache.set(key, result!) |
|____________________________________________________________|
ua
Accessor method to get and set UserAgent object used internally. You can call env_proxy for example, to get the proxy information from environment variables:
$meteo->ua()->env_proxy(1);
You can also set your own User-Agent object:
use LWP::UserAgent::Throttled;
my $ua = LWP::UserAgent::Throttled->new();
$ua->throttle('open-meteo.com' => 1);
$meteo->ua($ua);
API specification
Input
When called with no arguments acts as a getter; the input schema is empty.
When called with an argument the argument must be an object that responds to get:
{ ua => { type => 'object', can => 'get' } }
Output
{ type => 'object', can => 'get' }
FORMAL SPECIFICATION
___ UA ____________________________________________________
| self? : Weather::Meteo |
| ua? : OBJECT [can 'get'] (optional) |
|____________________________________________________________|
| result! : OBJECT [can 'get'] |
|____________________________________________________________|
| |
| PRE ua? defined ^ ~ua?.can('get') |
| => croak /must be an object that understands the get method/ |
| |
| POST ua? defined |
| => self?.ua = ua? ^ result! = ua? |
| |
| POST ~ua? |
| => result! = self?.ua (no state change) |
|____________________________________________________________|
AUTHOR
Nigel Horne, <njh@nigelhorne.com>
This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself.
Lots of thanks to the folks at https://open-meteo.com.
BUGS
Please report any bugs or feature requests to bug-weather-meteo at rt.cpan.org,
or through the web interface at
http://rt.cpan.org/NoAuth/ReportBug.html?Queue=Weather-Meteo.
I will be notified, and then you'll
automatically be notified of progress on your bug as I make changes.
SEE ALSO
- Test Dashboard
- Open Meteo API: https://open-meteo.com/en/docs#api_form
- Object::Configure
SUPPORT
This module is provided as-is without any warranty.
You can find documentation for this module with the perldoc command.
perldoc Weather::Meteo
You can also look for information at:
-
MetaCPAN
-
RT: CPAN's request tracker
-
CPANTS
-
CPAN Testers' Matrix
-
CPAN Testers Dependencies
LICENSE AND COPYRIGHT
Copyright 2023-2026 Nigel Horne.
Usage is subject to the GPL2 licence terms. If you use it, please let me know.